Objective: To explore more refined classification methods of congenital middle ear cholesteatoma (CMEC) based on two existing staging systems. Subjects and Methods: This study involved a retrospective data review of 57 patients (61 ears involved) with CMEC requiring the surgical treatment. Patients were classified into different stages according to Nelson, Potsic, and Modified Nelson staging system. Preoperative data and intraoperative findings were recorded. Results: The mean age at operation was 15 +/- 15.04 years with a median of 10 years. The main clinical manifestation was hearing loss (72.13%). CMEC mass was mainly located in the posterior portion of the tympanic cavity (65.57%). No patient was classified into Potsic stage II. The erosion of incus happened in all cases. Patients with Nelson type 2 and type 3 had erosions to the structures out of middle ear, such as dura mater, lateral semicircle canal, and facial canal. Postoperative follow-up time was more than 24 months. Recurrence occurred in four patients (6.56%), all of them in Nelson type 2, who had received canal wall down mastoidectomy (three cases) and canal wall up mastoidectomy (one case). Conclusions: Nelson staging system was more suitable for advanced CMEC patients than Potsic staging system. The rare case of Potsic stage II restricted the application of Potsic staging system. Moreover, since both of two staging systems do not distinguish the type of involved ossicles, the authors recommended to subdivide Nelson type 2 into type 2a and type 2b based on the erosion of the ossicular chain, as well as subdivide Nelson type 3 into type 3a and 3b based on the erosion of structures out of middle ear, which was named as Modified Nelson staging system.