Abstract: OBJECTIVE To investigate the influence of different administration timepoints on the endothelial protective effects of sodium tanshinone II A sulfonate(STS). METHODS Human umbilical vein endothelial cells(HUVEC) were divided into five groups, individually stimulated, including DMEM group, lipopolysaccharide(LPS) group, STS pre-treatment+LPS group, STS co-treatment+LPS group, STS post-treatment+LPS group. The final concentration of LPS in the experiment was 1 μg·mL^-1, and that of STS was 25 μg·mL^-1, LPS stimulation time was 12 h. After that, HUVEC viability was determined by CCK-8 assay. The protein concentration of inflammatory cytokine interleukin-1β(IL-1β) in HUVEC culture supernatant was detected by ELISA. The protein levels of nuclear factor κB(NF-κB) in HUVEC lysate were detected by Western blotting. The migration capacity of HUVEC was detected by wound-healing test. HUVEC apoptosis was observed under an optical microscopy, and the expression of apoptosis-related proteins including cleaved caspase-3 and cleaved caspase-9 were detected by Western blotting. RESULTS Compared with DMEM group, after LPS treatment, HUVEC cell viability was decreased; IL-1β and NF-κB protein expression increased; migration capacity impaired; increased apoptosis with the higher protein expression of cleaved caspase-3 and cleaved caspase-9(P<0.05). STS treatments could partially reverse these LPS-induced phenomena, among which the STS pre-treatment was most effective, while the STS post-treatment was with relative lower efficacy. CONCLUSION STS pre-treatment, co-treatment and post-treatment can partially reverse LPS-induced HUVEC dysfunction and apoptosis, among which the STS pre-treatment is most effective.