Sci-tech innovation re-lending helps guide financial institutions to increase financial support for sci-tech enterprises and leverage social funds to promote technological innovation. This paper explores the necessity and effectiveness of using sci-tech innovation re-lending as a long-term monetary policy tool by constructing a tripartite evolutionary game model involving "bank financial institutions—non-bank financial institutions—enterprises". The study finds that the evolutionary game among the three parties tends to stabilize in a state where financial institutions do not enter the tech-financial market, and enterprises opt not to innovate, thereby "depleting" the innovative vitality of sci-tech enterprises. As an external factor, sci-tech innovation re-lending can alter the stability of the tripartite game in the tech-financial market and stimulate the innovation enthusiasm of sci-tech enterprises. Therefore, it is highly necessary to use it as a long-term monetary policy tool. The sci-tech innovation re-lending policy has incentive effects, constraint effects, indirect effects, and interest rate effects, which can drive both bank and non-bank financial institutions to innovate in tech-financial services, thereby meeting the financing needs of scitech enterprises and encouraging their innovation. Based on the study's conclusions, the paper suggests expanding the scope of support, issuing quotas based on the lending categories, strengthening supervision, and enhancing policy coordination.