Which firms will make full use of public technological subsidies to advance their innovation level? Combining with resource based view,agency theory and signaling theory,this paper analyzes the three-dimensional moderating role of firm scale and ownership in the effect of public technological subsidies on firm innovation by the unbalanced panel data with 6 718 observations of 2 382 firms from Zhangjiang High-tech Park of Shanghai from 2006 to 2009.It comes to the following results: firstly,based on the correction of selection bias of government subsidies by propensity score matching,government subsidies play a significantly positive role in the promotion of firm innovation; secondly,firm scale can affect the exertion of the leverage effect of government subsidies on firm innovation,i.e.,larger firm scale leads to stronger positive incentive role of government subsidies in firm innovation; thirdly,the role of public technological subsidies in firm innovation varies with ownership,namely compared with state-owned enterprises,the non-state-owned enterprises can make better use of public subsidies to improve innovation; fourthly,the moderating role of firm scale also depends on ownership,and by comparison,the incentive role of government subsidies in innovation in non-state-owned enterprises constantly strengthens with the increase in firm scale.