Abstract According to the mechanism of "political connectionexternal resources R&D investment", combined with the feature of technical decisionmaking preferences, we explore the relationship of the four variables and the composition of the theoretical model by using SEM and choosing the data of listed companies in GEM except financial industry and insurance industry. We make some conclusions: After controlling the impact of some company's characteristics, political connection has the negative effect on R&D investment. But external resources would cover up the negative effect. Meanwhile, technical preference could moderate oppositely the negative effect. And both utilities can't interfere each other. The results of the study reveal the theoretical mechanism of political connection' impact on corporate R & D investment.