Objective:To analyze the clinical features, diagnosis and treatment of acute sinusitis related orbital cellulitis in children. Methods:The data of 51 cases with acute sinusitis comorbid with orbital cellulitis in Tianjin Children's Hospital from April 2016 to March 2021 were retrospectively analyzed. According to the extent of infection, the patients were divided into two groups:pre-septal orbital cellulitis(7 cases) and post-septal orbital cellulitis(44 cases). The general clinical characteristics, clinical manifestations, laboratory examination and treatment were compared between the two groups. Among them, 23 cases(6 in pre-septal orbital cellulitis group and 17 in post-septal orbital cellulitis group) were cured by medicine treatment; 28 cases were cured by surgical treatment after failure of medicine treatment. Results:There was no significant difference in age, gender and medical history between the two groups. Redness, swelling, heat and pain in eyelid was the most common clinical manifestations of orbital cellulitis in children, followed by fever, headache, runny nose, eye fixation, and vision loss. WBC count and neutrophils percentage were significantly higher in post-septal orbital cellulitis group. All children were followed up for 3 months to 3 years, 1 case was lost to follow-up, 50 cases had no recurrence and recovered well. Conclusion:Orbital cellulitis is a common and rapid developing complication of sinusitis in children. Early diagnosis and effective anti-infection treatment are very important for prognosis. Orbital CT plays an important role in the determination and evaluation of this complication. When conservative treatment is ineffective, surgical drainage in time can reduce the occurrence of serious ocular sequelae.