The main reasons for the insufficient innovation of the R & D team are the low enthusiasm and creativity of the team members, the knowledge communication and thinking collision of team members under good relationship are very important to the creativity of R & D team. This paper takes the ambidextrous learning as the mediating variable and the knowledge heterogeneity as the moderating variable, constructs the moderated mediating model of internal social capital affecting the R & D team creativity. Using the structural equation model, the empirical study based on the data of 308 R & D teams found that: firstly, the direct effect of structural capital and cognitive social capital on R & D team creativity is significant, while the direct effect of relational capital on R & D team creativity is not significant. Secondly, the ambidextrous learning plays a partial mediating role in the impact of structural capital and cognitive capital on R & D team creativity, while plays a whole mediating role in the relationship between relational capital and R & D team creativity. Thirdly, the knowledge heterogeneity is positively moderating the mediating effect of the ambidextrous learning. This study will helps to understand the influencing factors and mechanism of team creativity, and also provide a reference for improving the R & D team creativity.