| Objective To investigate the beliefs and attitudes towards sleep in depression patients comorbid with insomnia, and to explore its influence on sleep quality. Methods Depression patients with insomnia (n=61) and patients with primary insomnia (n=62) who met the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria in Beijing Anding Hospital affiliated to Capital Medical University were enrolled, and 64 healthy controls were recruited. All three groups received assessment of Sleep Dysfunction Belief and Attitude Scale (DBAS) and Pittsburgh Sleep Quality Index (PSQI), and depression patients with insomnia were evaluated with Hamilton Depression Scale 17-item (HAMD-17). The PSQI and DBAS scores of the three groups were compared by analysis of covariance. Multiple linear regression was used to analyze the influencing factors of PSQI score in depression patients with insomnia. Results The PSQI scores of depression patients with insomnia and primary insomnia group were higher than those of the control group (t=18.932, 187.610, P<0.01), and the DBAS scores of the two groups were lower than those of the control group (t=-5.561, -5.791, P<0.010). Taking the PSQI score of depression patients with insomnia as the dependent variable, the established multiple linear regression equations were statistically significant (F=14.095, R2=0.327, P<0.010). The prediction and control of sleep in DBAS and age were the influencing factors of PSQI score in these patients (B=-0.100, -0.279, P<0.05 or 0.01). Conclusion Compared with the normal, depression patients with insomnia have more dysfunctional beliefs and attitudes towards sleep, and poor cognition may be the influencing factor of their sleep quality.