Abstract: At present, China′s economy is in the process of transforming the development mode and optimizing the economic structure. Promoting economic development and technological progress by innovation, and re-engineering the power mechanism of economic growth are inevitable choices for cracking the growth dilemma. In the policy practice, as a policy test field, the national high-tech zone is the pioneering zone and demonstration zone for China to explore innovation-driven development road with relying on industrial agglomeration. The national high-tech zone is also responsible for guiding the development of high-tech industries. However, national high-tech zones are also faced with institutional inertia, dependence on the original development path, lock at the lower end of the value chain and other transition obstacles. Under this background, scientifically evaluating the technological progress effect of national high-tech zones and in-depth analysis of its mechanism will have important policy implications for further improving the construction of national high-tech zones, exploring effective policy measures to promote urban technological progress.
    By combing the relevant literature, we find that the existing literature rarely considers the establishment of a national high-tech zone as a research object, and examines the technological progress effect of the national high-tech zone. Furthermore, the relevant literature is often oriented to the evaluation results, but lacking the analysis of the mechanism of policy effect, which is obviously not conducive for our full understanding of the development dilemma of the national high-tech zone. Therefore, we expound the problems existing in the development of high-tech zones from the perspective of government behavior and industrial development. We have found that the national high-tech zone has made great progress in promoting scientific and technological progress, leading independent innovation, and promoting the development of emerging industries. However, the national high-tech zone is more prominent to promote local economic development. Under the Chinese-style decentralization system, local governments pay more attention to short-term political achievements. They trend to make the high-tech zone a policy environment that is not conducive to technological progress. When it comes to industrial development, the level of industrial agglomeration in high-tech zones is biased towards low-end, and innovation factors cannot be effectively transformed into technological progress. These phenomena form the research hypothesis of this paper, that is, the establishment of high-tech zones did not significantly promote the technological progress of urban.
    Based on the theoretical analysis, this paper uses the data of 279 prefecture-level cities in China from 2003 to 2015, and uses the Difference in Difference model to evaluate the impact of establishing national high-tech zones on urban technological progress. Furthermore, we divide production service industry into two categories: high-level production service industry and low-level production service industry. Then we take the agglomeration of producer service industry as an entry point and investigate the internal mechanism of why establishing a national high-tech zone cannot promote urban technological progress significantly. Finally, from the two aspects of "cost effect" and "productivity effect", this paper evaluates the repairing effects of infrastructure, manufacturing development, wage level, government R&D support, innovation personnel accumulation, and financial development on the above-mentioned transmission mechanism.
    The study shows that: (1) The establishment of national high-tech zones did not significantly promote regional technological progress. This conclusion is still robust after considering issues such as urban level, extreme value impact, spatial dependence, and parallel trend assumptions and so on; (2) The mechanism test shows that the reason for the above conclusions lies in the dislocation of the transmission mechanism which appear as "establishing a national high-tech zone → producer service industry agglomeration → urban technological progress". The establishment of a national high-tech zone has significantly promoted the accumulation of low-level producer service industries. However, the agglomeration of low-level producer services has little impact on urban technological progress. On the contrary, the high-level producer service industry which can promote technological progress effectively has not formed an agglomeration in the urban; (3) Further analysis found that improving infrastructure, promoting manufacturing development, increasing the wage level, enhancing government R&D support, expanding the accumulation of innovative personnel, and increasing the level of financial development can effectively repair the misplacement of transmission mechanisms and attract high-level producer service industries into the region. In addition, the "cost effect" of manufacturing development and the "productivity effect" of accumulating innovative talents is the most effective pathway.
    According to the research conclusions, we propose two policy inspirations. First, we should re-examine the strategic positioning of the national high-tech zone, focus on enhancing the scientific and technological innovation support of the national high-tech zone to the local economy, and avoiding excessive pursuit of the high-tech zone′s immediate economic performance. Carefully and scientifically selecting enterprises in the zone, and adopting high-level producer service enterprises as the main introduction target, avoiding excessive introduction of large projects with capital-intensive and quick output are also important. Second, it is necessary to rationally lay out manufacturing enterprises in the national high-tech zones, increase investment of scientific research and innovation, actively introduce high-level innovative talents, and provides guarantees for the productivity improvement of high-end producer service enterprises, hence giving full play of the "cost effect" and "productivity effect". Through these measures, we can effectively strengthen the positive effect of national high-tech zones on urban technological progress.
    Compared with the existing literature, the innovations of this paper are as follows: (1)this paper combs the problems existing in the development of high-tech zones from the aspects of policy implementation and industrial development, and quantitatively evaluates the policy effects of establishing national high-tech zones on urban technological progress, thus deepening our understanding on the development situation of national high-tech zones in theory and practice; (2) this paper deeply analyzes the internal transmission mechanism of the influence of establishing the national high-tech zones on urban technological progress, so as to provide a new perspective for understanding the development dilemma of national high-tech zones; (3) from the perspective of "cost effect" and "productivity effect", this paper investigates the effective ways of repairing the transmission mechanism, so as to provide an important grasp for targeted constructing of national high-tech zones.

Key words: national high-tech zone, technological progress, agglomeration of productive service industry, DID Model