To compare the lipid metabolites in the seminal plasma of normal fertile men from those of the patients with oligoasthenoteratozoospermia (OAT), and perform a pathway enrichment analysis on the differentially expressed lipids. According to strict inclusion and exclusion criteria, we recruited 30 males seeking medical attention in our Center of Reproductive Medicine and equally divided them into an OAT and a normal fertile control group. Employing the untargeted metabolomics approach, we screened the differential lipids in the seminal plasma of the OAT patients and subjected them to pathway enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database. In the OAT patients, the expressions of 22 lipids were significantly upregulated and those of 32 downregulated in the positive ion mode, and the expressions of 2 lipids upregulated and those of 12 downregulated in the negative ion mode. And 5 of the significantly downregulated lipids, namely anandamide(20:4,n-6), adrenic acid, cis-gondoic acid, (3'-sulfo)galbeta-cer(d18:1/24:1(15Z)) and palmitoylcarnitine, were associated with 4 branches and 8 sub-branches of the KEGG metabolic pathways, among which the differential lipid anandamide (20:4,n-6) was involved in the regeneration of the biological system in the KEGG sub-pathway and considered to be a significantly differentially enriched pathway. Lipid metabolites in the seminal plasma of OAT patients are significantly different from those in normal fertile males, and the differential lipid anandamide (20:4,n-6) may be involved in the regulation of sperm function and play an important role in male fertility.