Abstract: Strategy alliance is the important means of new ventures, overcoming LON and acquiring organizational legitimacy. However, we still know little about the relationship between strategy alliance of new ventures and organizational legitimacy. Drawing upon the structural equation model, this study examines the mediating effect of organizational learning and the moderating effect of environmental dynamism on the relationship between strategy alliance and organizational legitimacy. Our findings contribute to the literature in several ways. First, strategy alliance is able to significantly influence new ventures' legitimacy. Second, the mediating test shows that organizational learning acts as a mediator between strategy alliance and organizational legitimacy. Third, environmental dynamism moderates the relationship between strategy alliance and organizational learning. In addition, hierarchical regression analysis shows that the relationship between strategy alliance and organizational learning becomes stronger as environmental dynamism growing from low to high. Fourth, environmental dynamism moderates the mediating effect of organizational learning on the strategy alliance and organizational legitimacy linkage. Furthermore, conditional indirect effect test shows that the relationship between strategy alliance and organizational learning is more significant when environmental dynamism is higher. To sum up, our findings provide great implications for those future studies on strategy alliance of new ventures and organizational legitimacy in a transitional economy.