Abstract: OBJECTIVE To explore the proper intervention time and concentration of ursolic acid of Kuding tea on human nasopharyngeal carcinoma cell. METHODS Ursolic acid was extracted from the old leaves of Kuding tea and was then purified and tested. Different concentrations (5, 10, 20, 40, 80, 100 μmol·L^-1) of ursolic acid were used to interfere with human nasopharyngeal carcinoma cell for different lengths of time (24, 48, 72, 96, 120 h). MTT method was used in determining the effect of ursolic acid on cell proliferation inhibition. Microscopy method was used to observe cytotoxicity of ursolic acid. Flow cytometer method was used to determine apoptosis induction and cell cycle blocking effect of ursolic acid. RESULTS With 24 h of intervention time, the inhibitory rates of 40 and 80 μmol·L^-1 of ursolic acid of Kuding tea on NEC-2 cells were (41.21±0.25)% and (94.11±0.37)%, respectively; and both applications could block cells at G0/G1 phases with blocking rate of (73.41±0.17)% and (75.26±0.18)%, respectively. After 24 h intervention of 40 μmol·L^-1 of ursolic acid of Kuding tea, cell atrophy appeared, cell adhesion decreased, some cells died from fragmentations and cell’s number was obviously reduced. After 48 h intervention of 40 μmol·L^-1 of ursolic acid of Kuding tea, these effects were further strengthened and became more obvious. CONCLUSION　The ursolic acid of Kuding tea has strong intervention on human nasopharyngeal carcinoma cell. The concentration of 40 μmol·L^-1 and the observation time of 24 h are recommended in application.