Abstract: Objective To explore the effect of PKC on sperm motility and its mechanism. Methods After standard semen analysis, 30 healthy volunteers (sperm density ≥20×106 /ml, a≥25% or a + b ≥50% ) and 20 infertile males with asthenospermia (sperm density ≥20×106 /ml, a＜25% and a+b≤40%) were classified as control group and asthenospermia group,and the spermatozoa PKCβⅠin two groups were measured by flow cytometry(FCM). Moreover, spermatozoa in control group were incubated with PMA （PKC activator）for 15min,then treated with GF109203X（PKC inhibitor）for 15min, and the phosphorylation and protein expression level of ERK were detected by Western blot. Results The level of PKCβⅠin asthenospermia group decreased significantly compared with control group. After incubation with PMA, following the improvement of sperm motility, the phosphorylation level of ERK in spermatozoa increased significantly, however, after incubation with GF109203X, both sperm motility and phosphorylation level of ERK decreased significantly. Conclusions PKC may involve in the regulation of sperm motility through ERK signal transduction pathway，and the level of PKC in spermatozoa may play an important role in pathogenesis of asthenospermia.