Objective: To investigate the effect of triptolide on human oral cancer cell (HB) proliferation and phosphates and tensin homologue deleted on chromosome ten gene (PTEN) mRNA expression in oral cancer. Methods: The cancer cells were cultured in the medium containing triptolide of different concentrations for 24, 48 and 72 h. Methyl thiazolyl tetrazolium (MTT) method was used to test the rate of growth inhibition of cancer cells, flow cytometer to detect the change of cell cycle and reveres transcription-PCR (RT-PCR) to examine the expression of PTEN mRNA. The expression of PTEN protein was examined by Western blotting. Results: The rate of growth inhibition was (26.92 ± 0.14)%, (38.67 ± 0.11)%, (72.62 ± 0.89)% and (90.42 ± 0.28)%, respectively. The corresponding expression of PTEN mRNA was (3.59±0.21)%, (5.27±0.40)%, (7.18±0.44)% and (9.16±0.50)%, respectively and the corresponding A value of PTEN protein was 0.135±0.007, 0.410±0.020, 0.447±0.017 and 0.884±0.066, respectively. The proportion of G1 phase cells increased from (58.78±0.98)% to (84.13±0.47)%, but the proportion of S phase cells decreased from (25.40±0.43)% to (9.41±0.73)%. Conclusions The triptolide not only had inhibitory effect on the HB proliferation, but also affected the cell cycle.