Objective:To investigate the clinical significance of seminal plasma polymorphonuclear neutrophil elastase(PMNE) concentration and semen quality in male infertility.Methods:Semen samples of 941 patients admitted to the andrology department from June 2017 to December 2018 in Dalian Municipal Women and Children′s Medical Center were selected. According to the World Health Organization (WHO) fifth edition standards, the positive group had a leukocyte content &ge; 1 × 10 9/L, and the negative group had a leukocyte content < 1 × 10 9/L; the samples were divided into the inflammatory group and the non-inflammatory group with the PMNE concentration of 600 μg/L as the cut-off point, and the relationship between the PMNE, semen parameters and mycoplasma positive rate was analyzed; the samples were divided into sterile group and normal group according to WHO standard, and the relationships among semen routine parameters, PMNE concentration and mycoplasma positive rate were analyzed. Results:PMNE in the positive group was significantly higher than that in the negative group [(1823.29 ± 557.64) × 10 9/L vs. (480.60 ± 195.36) × 10 9/L], and PMNE concentration was positively correlated with leukocyte content ( P<0.05); the semen quality of the inflammatory group decreased, and the positive rate of mycoplasma was higher than that of the non-inflammatory group [(23.7%(71/299) vs. 11.5%(74/642)] ( P<0.05). The semen quality of the sterile group decreased, and the PMNE and mycoplasma positive rate were both higher than that in the normal group [(1 230.89 ± 489.09) × 10 9/L) vs. (596.78 ± 159.25) × 10 9/L, 34.7%(90/259) vs. 8.1%(55/682)]( P<0.05). Conclusions:There is a good correlation between the concentration of PMNE and the leukocyte content, which can be used as an index to evaluate the male reproductive system infection. The concentration of PMNE is closely related to semen quality, which has clinical value in the diagnosis of male infertility.