Abstract: Objective To analyze the clinical characteristics of idiopathic orbital inflammatory pseudotumor (IOIP) accompanied with sinusitis and explore the relationship between orbital pseudotumor and sinusitis. Methods In this retrospective study conducted in Chinese PLA General Hospital, 21 cases (28 eyes) with orbital pseudotumor accompanied with sinusitis and 48 cases (53 eyes) with simple orbital pseudotumor were collected from July 2007 to September 2015.The binocular incidence, age of onset and hospitalization time in patients with simple orbital pseudotumor or sinusitis-accompanied were compared. Results The binocular IOIP incidence in sinusitis-accompanied cases was 33.33% (7/21) and it was 10.41% (5/48) in simple orbital pseudotumor cases with significant differences (χ²=3.864, P=0.043).There was no statistically significant difference in the age of onset between simple orbital pseudotumor cases and sinusitis-accompanied cases (43.64±15.85) years vs (43.55±19.34) years, t=0.017, P=0.986.The cure rate of two groups showed no statistically significant difference (χ²=2.195, P=0.633).The average duration of hospitalization in simple orbital pseudotumor cases was 9 days and it was 12 days in sinusitis-accompanied cases with significant difference (Z=-2.289, P=0.023). Conclusion The binocular IOIP incidence in sinusitis-accompanied cases is significantly higher than simple orbital pseudotumor cases, and sinusitis should be considered in the diagnosis and treatment of idiopathic orbital inflammatory pseudotumor.