Objective To evaluate the influencing factors of secretory otitis media (SOM) after radiotherapy for nasopharyngeal carcinoma (NPC) systematically.Methods English databases (Pubmed, Embase, Cochrane library) and Chinese databases (CNKI, Wanfang, Weipu) were searched from the establishment of the database to August 15, 2021. According to the inclusion criteria and exclusion criteria, clinical research data were obtained. Meta-analysis of the involved studies was performed using Review Manager 5.4. The New Castle-Ottawa Scale (NOS) was used for quality evaluation. The binary variables were used to describe gender, staphylinus externus atrophy ≥30%, eustachian tube involvement, tumor stage (T1-T2, T3-T4), radiotherapy dosage ≥70Gy, and whether to use intensity-modulated radiotherapy (IMRT). The continuous variables were used to describe age and radiotherapy duration. The random effect model was used to evaluate the involved data.Results Seven case-control studies (757 patients) were included in this study. The results showed that age (P=0.35), gender (P=0.77) and whether to use IMRT (P=0.76) had no statistically significant differences in the effects of SOM formation after radiotherapy. Staphylinus externus atrophy ≥30% (P=0.01), eustachian tube involvement (P<0.01), tumor stage T1-T2 (P=0.02) and T3-T4 (P=0.02), radiotherapy dosage ≥70 Gy (P<0.01) as well as radiotherapy duration (P<0.01) had statistically significant effects on the formation of SOM after radiotherapy.Conclusion The atrophy degree of staphylinus externus ≥30%, eustachian tube involvement, tumor stage (T1-T2, T3-T4), radiotherapy dosage ≥70 Gy, and radiotherapy duration may be factors influencing the formation of SOM after radiotherapy for NPC.