Objective To establish a new N-stage system combining the number of metastatic lymph nodes and the ratio of metastatic lymph nodes for postoperative M0 stage inflammatory breast cancer patients. Methods Based on the data of inflammatory breast cancer patients in the SEER database, the number of metastatic lymph nodes and the ratio of metastatic lymph nodes were calculated.A new N-staging system was established and compared with the 8th edition of AJCC TNM staging system of breast cancer.The nomograph prognostic model was constructed and validated. Results The prediction performance of the new N-staging system for postoperative survival of M0 inflammatory breast cancer patients was better than the traditional N-staging system.The nomograph prognostic model showed an excellent clinical efficacy with a consistency index of 0.711. Conclusion The new N-staging system has good predictive performance for postoperative survival of M0 inflammatory breast cancer patients and can accurately reflect the prognosis.