The aim of this study was to investigate the feasibility and evaluate the clinical effects of transnasal marsupialization of maxillary cyst under nasal endoscope. Twenty patients with maxillary bone cysts were treated with endoscopic marsupialization. According to the location of the maxillary bone cyst, the opening window was selected in the nasal base or the inferior or middle nasal meatus. The cyst wall of the window was removed, and the fluid was drained out. The diameter of the opening window was more than 1 cm, so that the cyst and the maxillary sinus can be fused into a cavity. This ensured nasal drainage through the cyst cavity and nasal cavity or maxillary sinus. The patients were followed up for 6 to 18 months. No serious complications occurred. The cyst wall epithelialized 2 or 3 months after the operation, and the cyst cavity drained well with no recurrence. Intranasal marsupialization under a nasal endoscope is a feasible alternative for the treatment of maxillary cysts. It makes the procedure simple, safe, less traumatic, has definite clinical effects, and low recurrence rate. Especially suitable for maxillary cysts protruding into the nasal floor or maxillary sinus.