Under the background of knowledge economy, patent pool has become one of the important ways to accelerate the patent license and promote the application of patented technology. Based on the background of patent thicket and patent troll, this paper analyzes the patent pool and its characteristics from the perspectives of complementary patent, obstacle patent and competitive patent, and then explores the generated path of patent litigation in patent pool based on complementary patent from the refusal to patent license, patent licensing fees and patent restrictive clauses. The results show that there are three important patent litigations in the patent pool based on the complementary patent, but there are differences in the path of generating patent litigation in different aspects; The results not only provide academic support for deepening the theoretical research in this field, but also provide important implications for helping Chinese enterprises to optimize and effectively manage the patent pool and reduce the patent litigation.