Objective · To explore the effect of de-SUMOylation of p53SENP3 on its transcriptional activity in lung cancer. Methods · Lung cancer cell lines A549 (p53 wild type) and H1299 (p53 ) were used. Wild type p53 as well as sumoless mutants K386R or E388A were introduced into the cells. Co-immunoprecipitation was performed to detect SUMOylation of p53 under resting status or oxidative stress. Immunofluorescence was applied to observe the localization of p53 WT and K386R or E388A. Dual luciferase reporter assay and quantitative real-time PCR of p21 were performed to monitor the transcriptional activity of p53 WT and K386R or E388A. Growth curve was analyzed to demonstrate the effect of p53 WT and K386R or E388A on cell proliferation. Results · SENP3 was able to mediate de-SUMOylation modification of p53 under oxidative stress. Similar to WT p53, K386R and E388A p53 kept nuclear localization. Further, SENP3 knockdown or oxidative stress did not induce translocation of p53 nucleus to cytoplasm. However, compared to WT, the transcriptional activation of K386R and E388A p53 were inhibited. Moreover, SENP3 inhibited the activity of p53 in A549. K386R and E388A p53 attenuated the inhibitive activity on cell proliferation in H1299. Conclusion · SENP3-mediated de-SUMOylation of p53 is one of mechanisms of its inactivation as tumor suppressor in lung cancer.