Aim To observe the effect of OX40-OX40 ligand （OX40L） interaction on the expression of cyclophilin A （CyPA） in mice aortic vascular smooth muscle cell （VSMC）. Methods Patch-attaching method was used for primary culture of mouse aortic VSMC. The expression of OX40L mRNA and protein in VSMC were measured by real-time quantitative PCR （RT-PCR） and flow cytometry （FCM）, respectively. The levels of CyPA inside and outside of the VSMC was determined by RT-PCR and Western blot. Results The expression of OX40L mRNA and protein was time-dependently induced by tumor necrosis factor-α （TNF-α） plus lipopolysaccharide （LPS）, the mRNA expression peaked at 24 h （5.967±0.252 vs 1.000±0.000, P<0.05）, and the expression of protein peaked at 36 h （61.900±2.551 vs 20.967±0.451, P<0.05）. The expression of CyPA mRNA was time-dependently induced by soluble OX40 （sOX40）, and peaked at 90 minute （1.799±0.098 vs 1.000±0.000, P<0.05）. And abundant CyPA was gained in supernatant at 2 h （1.119±0.059 vs 0.281±0.038, P<0.05）, whereas, we didn’t observe the change of CyPA protein inside the VSMC compared to the control. Notably, the sOX40 revulsive elevations of mRNA （1.105±0.091 vs 1.799±0.098, P<0.05） and protein （0.635±0.040 vs 1.119±0.059, P<0.05） can be blocked by anti-OX40L monoclonal antibody.