Abstract: Business model innovation(BMI) is becoming the important carrier of start-ups growth strategy under internet era. Business model theory regards BMI as a market-oriented innovation which may gain first-mover advantage, and institutional legitimacy theory points out that high innovative start-ups may face legitimacy obstacles. How does BMI promote start-ups growth in the institutional context. Around this problem, by conducting an empirical study of 512 sample new ventures, we combine legitimacy perspective with business model theory, explore that how BMI influences new venture performance mechanism, and investigate the moderator of policy orientation and the mediator of legitimacy. The results show that: (1)BMI is positively related to legitimacy and new venture performance; (2)Organization legitimacy mediates partially the relationship between BMI and new venture performance; (3)policy orientation moderates the link between BMI and legitimacy; (4)the interaction of BMI and policy orientation makes an indirect effect on new venture performance through legitimacy’s mediation.