Abstract: Drawn on Knowledge-Base Theory (KBT) and the perspective of organizational ambidexterity, we explore the relationship among ambidextrous integration of knowledge(including efficient integration of knowledge and flexible integration of knowledge), entrepreneurial capability and high-tech new venture performance.Using the data from 279 Chinese high-tech new ventures, the empirical analysis results show that ambidextrous integration of knowledge has a positive effect on both high-tech new venture performance and entrepreneurial capability. Moreover, entrepreneurial capability is the complete mediator in the relationship between ambidextrous integration of knowledge and high-tech new venture performance. Our research provides deeper insights into KB, helps fill the extant research gap and promotes the development and integration of KBT and research on entrepreneurial capability. This research also offers critical guidelines for new ventures to integrate entrepreneurial knowledge efficiently and flexibly for entrepreneurial capability building and thus increase their performance in the context of transition economies.