Background: To investigate effect of radiosensitization of [Ru(bpy)₂(phen)]Cl₂ complex on nasopharyngeal carcinoma cell line CNE1 and its mechanism. Materials and Methods: Nasopharyngeal carcinoma cell line CNE1 in vitro culture was divided into control group, light irradiation group (4 Gy, 6 MV photonic line), simple metal ruthenium complex treatment group (Ru group, 100 μmol/L [Ru(bpy)₂(phen)]Cl₂) and metal ruthenium complex combined with radiotherapy group (Combined radiotherapy group, cells were irradiated with 4 Gy and 6 MV photons at 2 days after 100 μmol/L [Ru(bpy)₂(phen)]Cl₂). Results: Transcriptional level of P53 gene in combined radiotherapy group was higher than that in the other groups (P<0.001). Inhibition rate of combined radiotherapy group was higher than that of Ru group and irradiation group (P<0.001). Apoptotic rate was the highest (P<0.05) in the combined radiotherapy group, and irradiation group was higher than Ru group and control group (P<0.05). Survival rate of Ru group was lower than that of control group under the same radiation dose (P<0.05), and the radiotherapy sensitization ratio was 1.227 (Dq ratio). Conclusion: [Ru(bpy)₂(phen)]Cl₂ increases the sensitivity of nasopharyngeal carcinoma cell line CNE1 to X-ray, which may be related to increase of P53 gene expression.