Objective To investigate the sensitivity of tumor cells to photodynamic therapy(PDT), and to select the optimal photo-dose and photo density for PDT to the cultured cells. Methods Cells of SHEE and SHEEC cell lines were divided into 21 groups randomly,after 24 h inoculation, the cells accreted on paries of culture capsule completely, we replaced M199 complete culture solution with 30 μg/rnl Photofrin-Ⅱ solution 100 μl and then replacd with M199 complete culture solution without Photofiin-Ⅱ after 150 min of incubation in Photofrin-Ⅱ. Within 15 min,we dealed the cells with PDT using Photofrin-Diomed 630 under three different power densities:25 raW/cm~2,50 mW/cm~2 and 100 mW/cm~2 for 10 s,20 9,30 s,50 s, 100 s, 150 s and 200 s respectively,and then continue for 24 h culture. We examined the inhibiting effect on cell line SHEE and SHEEC under PDT by the method of CCK-8. Results There was no significant difference in the inhibition ratio with same power density of PDT between cell line SHEE and SHEEC under the concentration of 30 μg/ml Photofrin-Ⅱ. However, the inhibition ratio increased with the raising of photo-dose of PDT,but there was a platform stage after the 2.5～30 J/cm~ 2 photo-dose. Conclu-sion The difference for photodynamic sensitivity between human immortalization esophageal epithelial cell line SHEE and the malignant transformation cell line SHEEC is not significant. The targeting of PDT to malignant tumor cell may not be involved in the photosensitivity for tumor cell.