Abstract: Objective To investigate the effect of ultraviolet B (UVB) on HaCaT cells for providing technical support to prevention of ultraviolet damage.Methods Cultured HaCaT cells were exposed to UVB at intensity of 0,10,30,and 60 mJ/cm² and subsequently incubated for 12 hours.Flow cytometry (FCM) was used to detect proliferation rates of HaCaT cells exposed to different intensities of UVB.Commet method was used to detect DNA damage of the HaCaT cells.Results The early apoptotic rates of control group,10,30,and 60 mJ/cm² UVB groups were 1.2±0.14%,2.23±0.37 %,4.13±0.29%,and 5.97±0.17%;the late apoptotic rates were 2±0.13%,7.63±0.52%,23.36±0.98%,and 40.46±1.39%,with statistically significant difference (P<0.05).The tail moments (TM) of control group,10,30,and 60 mJ/cm² UVB groups were 0.13±0.25,21.78±2.31,53.48±5.66,and 79.16±7.47;the olive tail moments (OTM) were 0.32±0.47,16.17±1.96,36.43±2.89,and 51.71±1.87,with statistically significant difference (P<0.05).Conclusion UVB can induce cell apoptosis and DNA damage and DNA damage may be one of the causes of some rare diseases among residents living in plateau area.