Based on the perspective of knowledge governance， this paper constructs a serial mediating model of the relationship among geographic proximity， knowledge governance， knowledge sharing and collaborative innovation performance of clustered agricultural e-commerce firms， and explores the influence path of geographic proximity on collaborative innovation performance. In addition， the network relationship strength is introduced as a moderating variable to clarify the boundary of the serial mediating effect between knowledge governance and knowledge sharing. Based on the survey data of 341 clustered agricultural e-commerce firms， this paper analyzes the direct effect of geographic proximity on collaborative innovation performance， and tests the independent mediating effect and serial mediating effect of knowledge governance and knowledge sharing， as well as the moderating effect of network relationship strength by using multi-level regression and bootstrap analysis methods. The results show that： Geographic proximity has a positive impact on collaborative innovation performance. Knowledge governance mediates the relationship between geographic proximity and collaborative innovation performance. Knowledge sharing mediates the relationship between knowledge governance and collaborative innovation performance. Knowledge governance and knowledge sharing play a serial mediating effect between geographic proximity and collaborative innovation performance. Network relationship strength positively moderates the serial mediating effect of formal knowledge governance and explicit knowledge sharing. Therefore， clustered agricultural e-commerce firms should grasp the development opportunity of digital economy， make use of cluster location advantages and industrial resources， stimulate the dual effects of formal knowledge governance and informal knowledge governance， establish excellent knowledge sharing relationship with cooperative firms， and then realize high-quality collaborative innovation and development.