Abstract: Which kinds of government supports can promote the growth of small and medium-sized enterprises is a crucial topic for theory. In this study, 842 private SMEs were selected as samples to analyze the influence of innovation vouchers, a new type of government support, on the growth of SMEs. The results show that innovation vouchers have a significantly positive effect on the growth of SMEs. Furthermore, with low financing constraints or with low marketization degree, the positive effect of innovation vouchers on SMEs’ growth is more significant. The robustness test still confirmed the above conclusions. In terms of the mechanism of influence, innovation vouchers promote growth through innovation performance and innovation efficiency. This study expands the study of the government's macro policies on the behavior of private SMEs and puts forward the mechanism that influences the evolution of SMEs, which will benefit the government's decision-making.