Abstract: Knowledge search is an important way to improve the innovation capability of enterprises. Based on the panel data of 88 high-tech SMEs in the electronic equipment manufacturing industry, we constructs the empirical model to explores the effect mechanism of the breadth and depth of knowledge search on the innovation capability of high-tech SMEs and the moderating effect of knowledge element relations in different dimensions. The results show that both breadth and depth of knowledge search have an inverted U-shaped relationship with SMEs’ innovation capability. In the process of search breadth affecting the innovation capability, the knowledge complementarity plays negative moderating role, but the positive effect of knowledge substitutability are only partially supported by the data. The knowledge substitutability negatively moderate the impact of search depth on innovation capability, but the moderating effect of knowledge complementarity do not work. The result of research is of great significance to the innovation decision of high-tech SMEs.