Human osrvix Hela cells were synchronized, collected and seeded into Rose chambers for experiment. Cells at G1, S and G2 stages were then treated in the medium with hematoporphyrin (HPD) and irradiated by a laser mierobeam at 632.8nm. It was found that in case of the occurrence of primary and significant visible damage, cells at S stage showed the earliest, G2 stage the next, and G1 stage the latest. Variance analysis demonstrated that the variations are statistically significant.