Improving innovation capabilities is the key driver for the sustainable development of small and micro enterprises（SMEs）. Based on the survey data of China’s small and micro enterprises，this paper uses 2SLS method and multiple treatment effect model to empirically evaluate the policy mix effects of two tax incentives on the innovation of SMEs. The results show that：halving of corporate income tax has a significant incentive effect on innovation of small and micro enterprises，while the effect of increasing the value-added tax threshold is not significant，it helps to enhance the incentive effect of halving corporate income tax，which is manifested as a positive policy synergy. Mechanism analysis shows that the policy mix helps reduce SMEs’liquidity constraints and tax burden，and releases a positive signal effect. Furtherly，the positive effects of the policy mix significantly exist in the firms such as these enterprises facing with strong capital demand，technologybased enterprises，having good prospects of industries’future，high concerns about the social and economic status，and enterprises located in the middle and western regions. The conclusions can help to provide further empirical inspiration for the implementation of the new small and micro enterprise tax and fee reduction policies.