Inflammation of the left maxillary sinus, also commonly known as sinusitis, is caused by chronic inflammation of the nasal cavity invading the sinus mucosa, which leads to inflammatory edema, hyperplasia and even exudation of the sinus mucosa, and the patient will experience symptoms related to nasal congestion, yellow nasal discharge, headache, and facial distention and pain. On examination, congestion and edema of the left turbinate can be found, and yellowish secretions can be found at the opening of the maxillary sinus. If the patient is diagnosed with left maxillary sinusitis, the patient needs symptomatic anti-inflammatory treatment, because sinusitis is usually a bacterial infection and is mostly seen in Staphylococcus aureus. Ceftriaxone sodium, cefazolin sodium, cefotaxime sodium can be entered, while the left maxillary sinus can be punctured and irrigated once a week, and repeated treatment will gradually heal in about a month. In contrast, recurrent chronic maxillary sinusitis requires surgical treatment for complete cure.