Objective To explore the effect of insomnia disorder on social function， and the chain mediation effect of fatigue and depression. Methods A total of 131 patients with insomnia disorder， who were treated in the sleep clinic of Beijing Huilongguan Hospital from February to August 2022， were recruited as the research objects by convenience sampling method. The insomnia level， fatigue status， depressive mood and social function of patients were assessed by Pittsburgh Sleep Quality Index （PSQI）， the Multidimensional Fatigue Inventory-20 （MFI-20）， Patient Health Questionnaire-9 （PHQ-9）， Sheehan Disability Scale （SDS）. Spearman correlation analysis was conducted to investigate the correlation among patients' social function， depressive mood， insomnia disorder and fatigue. The chain mediating model was constructed by Model 6 in SPSS PROCESS V4.1 plug-in. Non-parametric percentile Bootstrap method with deviation correction was used to test the significance of the mediation effect. Results The score of SDS was （14.12±6.46）， PHQ-9 （9.23±5.29）， MFI-20 （57.97±11.82）， PSQI （15.74±4.89）. The correlation analysis results showed that there was a positive correlation between patients' social function， depression， insomnia， and fatigue （r=0.383-0.657， P ＜ 0.01）. The results of mediating effect showed that the total effect value was 0.736. Insomnia had a direct effect on social function， and the effect value was 0.294， accounting for 39.95% of the total effect. Fatigue and depression had a mediating effect between insomnia and social function， with effect value of 0.266 and 0.089， respectively， accounting for 36.14% and 12.09% of the total effect. Fatigue and depression had a chain mediating effect between depression and social function. The effect value was 0.086， accounting for 11.68% of the total effect. Conclusions The insomnia situation of patients with insomnia disorder can damage their social function， and it can also indirectly damage their social function through the chain mediating effect of fatigue and depression emotions.