Abstract: With the deepening of "going global" strategy and the rapid growth of cross-border M&A of Chinese enterprises, does cross-border M&A promote the quality of technological innovation of Chinese enterprises? How to select suitable objects of cross-border M&A to effectively improve the quality of technological innovation? Under the background of accelerating technology update iteration and increasing R&D cost, and under the strict control of key technologies by leading enterprises in developed countries, the research and answers to these questions will promote Chinese enterprises to "go out" and embed into foreign innovation networks, effectively allocate foreign advanced innovation resources and achieve technology catch-up. Scholars have conducted in-depth research on the technological innovation effects of cross-border M&A, most of the conclusions are that cross-border M&A can help enterprises obtain technological spillovers and promote innovation performance. However, the above researches used the sample of multinational enterprises in developed countries. In order to avoid the spillover effects of R&D, multinational enterprises in developed countries usually concentrate the R&D activities of the target enterprises to the corporate headquarters. In order to strengthen their ownership advantages, multinational enterprises transfer knowledge, technology and other intangible assets to the target enterprises through internal trade. Compared with the multinational enterprises in the technology leading countries, the multinational enterprises in emerging markets do not have the ownership advantage. They tend to evade the intellectual property barriers through cross- border M&A, acquire the core cutting-edge technology of the target enterprises, and achieve technology catch-up. The cross-border M&A in emerging markets is different from that in developed countries. Existing researches usually only focus on the impact of cross-border M&A on the scale of innovation output represented by patent count, and ignore the effects of cross-border M&A on innovation quality. In fact, the innovation content or value of different patents is uneven. Only using the number of patents and ignoring the difference of patent quality may lead to the conclusion biased. Although different investment motivations are distinguished in the related researches of cross-border M&A, most of the existing researches regard cross-border M&A projects as homogeneous under the same investment motivation scenario, few of them consider the complementarity between the knowledge base of the enterprise itself and the technical knowledge of the target enterprise, the technology complementarity of both sides is different, and the innovation performance of the cross- border M&A is different. With the rapid growth of cross-border M&A, whether Chinese enterprises promote the quality of innovation through cross-border M&A is a practical question that must be explored and answered. As an important way to acquire external knowledge and advanced technology, cross-border M&A mainly affects the innovation behavior of enterprises through the following channels: (1) the acquisition effect of innovation elements; (2) speed economy effect; (3) platform effect; and (4) embedding effect of innovation network. This paper puts forward the following hypotheses 1: Cross-border M&A promotes the innovation quality of acquiring enterprises. The relevance of technological knowledge between cross-border M&A parties is a prerequisite for learning and integrating external knowledge. However, the relevance is too high to stimulate new ideas. There are some differences in the technological knowledge between both sides, which is helpful to the research on the divergence of acquiring enterprises and the creation of new technological orbit. However, the difference of technical knowledge between both sides is too large, the cost of understanding, absorbing and integrating each other′s technical knowledge is high, which is not conducive to innovation synergy. When the technological knowledge of both sides shows complementarity, the innovation performance is significantly improved. This paper puts forward hypothesis 2: the complementarity of technological knowledge between both sides of cross-border M&A can moderate the innovation quality effect of cross-border M&A. Through the logit model, we empirically test the influencing factors of enterprises′ cross-border M&A behavior, obtain the tendency score and the control group matching with the observation group. By mining patent documents, the innovation quality index is comprehensively characterized by three indicators: the coverage of patent technology, the size of patent family and the number of patent citations. On the basis of propensity score matching, the double difference DID model is constructed. It is found that cross-border M&A of Chinese enterprises actively promotes the scale of technological innovation output. However, cross-border M&A in the first lag period has a significant restraining effect on the quality of technological innovation. In the early stage of M&A, due to the integration of technological resources, the friction effect is better than the synergy effect, and they are not significant in the second and third lag period, which means that as the time goes by, the restraining effect of friction on the quality of technological innovation is gradually released. That is to say, there is a "quantitative change" of innovation output but no "qualitative change" in innovation in cross-border M&A of Chinese listed companies. The reason is that enterprises have access to the advanced innovation resources of overseas target enterprises through cross-border M&A, which enriches the innovation knowledge of enterprises to a certain extent and helps the enterprises to apply for more patents. However, whether the patent applied for after cross-border M&A has a slight improvement of the original process or technical scheme, or a breakthrough innovation is affected by technology complementarity of both sides of cross-border M&A. From the perspective of reverse technology transfer, that sample enterprises try to obtain advanced technology transfer from the target enterprises through cross-border M&A to improve the technological innovation ability has not come into reality yet. The intermediary model is used to empirically analyze the moderating effects and influence mechanism of technology complementarity on innovation quality effect of cross-border M&A. It is found that technology complementarity has a positive moderating effect on the innovation quality effect of cross-border M&A. when technology complementarity between M&A parties, it is conducive to achieving "growth synergy". The technological complementarity both parties positively enriches the technological knowledge diversification and improves technological innovation efficiency of enterprises. The findings provide valuable reference for Chinese enterprises to effectively implement cross-border M&A, allocate innovation resources and improve innovation quality.

Key words: cross-border M&A, quality of innovation, technology complementarity