Based on the analysis of current literature, considering the characters of clusters, we construct a model of the influencing mechanism that firm's openness has on innovation performance with the network centrality and absorptive capacity as the moderating variables and the knowledge acquisition as the mediating variable. 116 firms in three industrial clusters in Zhejiang Province are selected as the research objects, and the regression analysis and other statistical methods are used for empirical validation.The result shows that, first, knowledge acquisition plays an intermediary role in the influence of openness on innovation performance, that is, the innovation performance of the cluster firms is influenced by the openness through knowledge acquisition.Second, the absorptive capacity plays a moderating role in different stages of the formation of innovation performance. The potential absorptive capacity is conducive to strengthening firms to obtain the knowledge from openness.The realized absorptive capacity plays a moderating role during the processes that knowledge abtained transform to innovation performance. Third, the higher the network centrality, the more significant the positive effect of the open width of the cluster firms to knowledge acquisition. The research result will help Chinese firms to promote open innovation policy options.