Objective · To investigate the effect of sinus inflammation on the prognosis of blowout orbital fracture (BOF) patients. Methods · With the retrospective study method, 66 BOF patients at Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from December 2018 to August 2019 were included and divided into sinus membrane thickening group (SMT group, n=48) and no sinus membrane thickening group (NSMT group, n=18). The corrected vision, diplopia, eye movement disorder, and exophthalmia of patients were compared between the two groups. In this study, the χ2 test, one-way analysis of variance and multiple regression equations were used to analyze the correlation between SMT and the prognosis of BOF. Results · Postoperative diplopia and eye movement disorder in the NSMT group compared with the SMT group were milder (both P=0.000). The difference in exophthalmia and changes in corrected visual acuity were not correlated with the thickening of sinus membrane. Conclusion · Sinus inflammation is correlated with the recovery of diplopia and eye movement disorder of BOF.