A submucosal cyst of the maxillary sinus usually presents with nasal congestion, runny nose, persistent dull headache, pain in the maxillary teeth, dyspnea, and diplopia. 1. Submucosal cyst of maxillary sinus is a relatively common benign lesion of maxillary sinus. It usually manifests as blisters growing in the maxillary sinus and is accompanied by symptoms such as nasal congestion and runny nose. 2. It may also hinder the normal functioning of the maxillary sinus cavity, such as hindering breathing and causing breathing problems, the blisters are too large and cause the sinus cavity to swell into a rounded shape and press on the surrounding nerves and press on the teeth, resulting in tooth pain. Pressure on the eye leads to mild upward displacement of the eyeball on the affected side and diplopia. 3. The treatment of submucosal cyst of maxillary sinus is often decided according to the size of the maxillary sinus cyst and the patient’s clinical manifestations. If there is no obvious discomfort and the size is small, it can be treated conservatively by paying attention to the diet, keeping the nasal cavity hygienic and avoiding infection. If the size of the cyst is large and accompanied by uncomfortable symptoms, it is recommended to take radical surgery of the maxillary sinus. If the patient has any adverse reaction or if the cyst is ruptured due to squeezing, he should go to the hospital for examination and treatment in time to avoid the expansion of the condition.