Promoting knowledge acquisition through network relationship is an important means to improve the performance of collaborative innovation in industrial clusters. Base on the data gathered through a survey of 206 enterprises in manufacturer clusters, this empirical study examines the mediating effect of knowledge acquisition in the relationship of cluster network relationship and collaborative innovation performance of firms by the method of multiple regressions. The results show that all of the network strength, network quality, network power and the stability of the network in cluster network relationship have significant positive impacts on collaborative innovation performance of firms. Furthermore, knowledge acquisition completely mediates the relationship between anyone of the network strength, network quality and the stability of the network and collaborative innovation performance of firms. However, knowledge acquisition has an incomplete mediating effect in the relationship of network power and collaborative innovation performance of firms. Finally，some suggestions are put for to improve the performance of collaborative innovation in industrial clusters.