Knowledge power plays an important role in venture's innovation capability and sustainable competitive advantage, but the formation mechanism of knowledge power is not clear at present. Therefore, this paper integrates two network's aspects of relationship and structure, puts forward the analysis framework of alliance capability, network position transition and knowledge power, to explore the impact of new ventures' alliance capability, location transition on their knowledge power, and conducts an empirical analysis based on 177 enterprises sample. Results show that, new ventures' alliance exploitation capability and alliance management capability have positive impact on their knowledge power in knowledge network, and network location transition plays a mediating role between alliance capability and knowledge power. Specifically, the enhancement of network medium plays a partial mediating role between alliance exploitation capability and knowledge power, also plays a complete mediating role between alliance management capability and knowledge power, but the increase of network centrality doesn't play a significant mediating role.