Aim To evaluate the effects of cyclooxygenase(COX)inhibitor and recombinant human CD40 ligand(rhCD40L)on human α₂(Ⅰ)collagen promoter.Methods After amplification and identification,pCOLH_22.4 and pCOLH_21.6,a plasmid containing PCAT3-enhancer,were transfected into human vascular smooth muscle cell(VSMC)using Lipofectamin transfection reagent.The expression of target gene and protein were measured by CAT enzyme linked immunosorbent assay(ELISA)kit.The effects of COX inhibitor and rhCD40L on CAT activity were evaluated after transfection.Results Compared with the control group,the CAT activities were inhibited by rhCD40L.NS-398 and aspirin could reverse the CAT activities inhibited by rhCD40L;the effect of NS-398 was stronger than that of aspirin.Conclusion rhCD40L could inhibit the activities of human α₂(Ⅰ)collagen promoter by COX pathway partly.