Abstract: Objective To describe the clinicopathological characteristics of bilateral primary breast cancer(BPBC) and analyze the prognostic factors. Methods A retrospective chart review was conducted on 68 patients diagnosed as BPBC at the Breast Center, Peking University People's Hospital. The clinicopathological characteristics were analyzed among patients with bilateral breast cancer using Spearman Rank Correlation. The prognosis factors were analyzed using COX regression analysis. Results Of all the breast cancer patients, BPBC accounted for 3.2%. The first onset age of BPBC patients was earlier than that of unilateral breast cancer patients(P=0.007). When 12 or 24 month of interval time was used to separate synchronous bilateral primary breast cancer(sBPBC) and metachronous primary breast cancer(mBPBC), the cumulative survival rate of sBPBC patients was lower than that of mBPBC patients(P=0.018，P=0.000); there was a significant difference in the survival between patients with invasive lobular breast cancer and invasive ductal breast cancer, from the diagnosis of the second primary tumor(P=0.036). Using the Cox multivariate model, tumor stage, interval time of two tumors and hormone receptor status of the second primary tumor affected the survival of BPBC patients significantly(P=0.02, P=0.02, P=0.049). Conclusion The onset age of BPBC patients was early. The survival of sBPBC patients was worse than that of mBPBC patients. Tumor stage, interval time of bilateral breast cancer, pathological type of the second primary tumor and hormone receptor expression have prognostic significance on BPBC patients.