Abstract:     The innovation of small and medium-sized enterprises (SMEs) drives the national high-quality and self-reliance development and it is the basis for consolidating common prosperity. In addition, enterprise innovation has the characteristics of positive externality. Therefore, the State has issued the "specialized, refined, characteristic and innovative" qualification accreditation policy, the soul of which is to empower enterprise technological innovation. This paper explored the mechanism and impact of the policy on the technological innovation of SMEs, and based on the data of A-share listed companies in Shenzhen and Shanghai from 2015 to 2021, it constructed a time-varying DID model for empirical analysis. The research found that: (1) in general, the qualification accreditation policy of "specialized, refined, characteristic and innovative" enterprises can significantly improve the technological innovation level (R&D investment and innovation output) of SMEs, but the incentive effect is not strong; (2) the mechanism test showed that the policy can promote the technological innovation of SMEs through the "resource bias" effect, and there are heterogeneous effects of "qualification upgrading" and "regional difference"; (3) Compared with provincial and municipal qualification accreditation policies, the national "specialized, refined, characteristic and innovative" qualification accreditation policy has a stronger incentive effect on the technological innovation of SMEs, which verifies the scientific nature of policy gradient cultivation. However, it also reflected that there may be problems such as lax qualification examination and insufficient motivation for continuous innovation in provincial and municipal qualification accreditation. (4) Compared with less developed regions, the absorption effect of policies in regions rich in economic and political resources is weaker, so policies should be adapted to local conditions to avoid the risk of regional policy saturation. This paper has not only expanded the relevant research on the impact of "specialized, refined, characteristic and innovative" qualification accreditation policy on enterprise innovation, but also provided some experiences for optimizing the policy to continuously promote the high-quality development of SMEs.

Key words: "specialized, refined, characteristic and innovative" enterprise, enterprise technological innovation, high-quality development