Abstract: External knowledge search plays a critical role with rapid innovation. Different search strategy results in different innovation performance. From the perspective of formal/informal knowledge search，with the impact of depth-driven/breadth-driven knowledge search strategy on innovation performance，the modificatory effect of relational embeddedness and knowledge tacitness is discussed．Through the investigation and empirical analysis of 161 questionnaires, we found relational embeddedness has a positive modificatory effect between depth-driven formal/informal knowledge search strategy and innovation performance, and knowledge tacitness has a positive modificatory effect between breadth-driven formal knowledge search strategy and innovation performance.