Objective To identify serum proteome of ejaculation praecox(EP) with Shen-yang de- ficiency, and to explore its pathogenesis of EP in the protein-protein interaction ( PPI) network. Methods The serum samples were respectively collected from 4 EP with Shen-yang deficiency patients and 4 healthy controls. After the serum proteome of EP with Shen-yang deficiency was obtained, the technology of isobaric tags for relative and absolute quantitation (iTRAQ) was adopted for identification. The STRING data- base was applied to construct the PPI network whose function was analyzed through bioinformatics meth- ods. Results A group of 238 serum proteins were identified in total, of which, 162 proteins reached the strict quantitative standard. Nine proteins were differently expressed, including 1 up-regulated and 8 down-regulated. The constructed PPI network was constituted by 72 protein nodes and 283 protein couples, and could be clustered to 16 clusters, in which 10 clusters were composed of 3 or more proteins. Each cluster could be found with a core protein correspondingly. The core protein of C3,C5,C1S and MASP2 were all main constituents of complement system, whose function involves in biological process of complement ac- tivation. Conclusions The protein models in PPI network of differently expressed serum proteome about EP with Shen-yang deficiency were functional enriched in the biological process of complement activa-, tion; which indicate that a immune dysfuction dominated by abnormal process of complent activation may' be one of the main mechanisms of EP with Shen-yang deficiency.