Abstract: Innovation is the "main engine" of high-quality development of enterprises, leading the transformation of enterprise
development from factor-driven to innovation-driven. Taking panel data of 2, 253 listed manufacturing companies from 2014 to 2018 as
the research object, multiple regression and adjustment effect were used to test the impacts of extra tax deduction policy of r&d expense
on innovation investment, the adjustment effects of enterprise growth and the existence of property right heterogeneity. The results show
that:（1）there is a significant positive correlation between r&d tax incentive intensity and innovation investment intensity, and
enterprise growth can positively adjust the incentive effect of r&d tax incentive policy on innovation investment;（2）the incentive effect
of r&d expense extra deduction policy on innovation investment is more significant in private enterprises. Enterprises should actively
grasp the preferential fiscal and tax policies such as the extra tax deduction policy for r&d expenses, so as to realize the incentive effects
of the preferential tax policies on enterprises to actively carry out innovation activities and increase innovation investment.