Objective To explore the characteristics of comorbidity of chronic insomnia disorder（ CID） and restless legs syndrome（ RLS）. Methods A consecutive case series of CID were enrolled into the study. The patients' general information， etiological subtype， RLS symptoms investigation and RLS symptom severity scale were recorded. All patients were divided into CID with RLS group（ CID+RLS） and CID without RLS group（ CIDRLS）， and the distribution of etiological subtype was compared between two groups. Results 117 cases of CID were enrolled from 122 consecutive cases， the other 5 cases were eliminated because of unable cooperation. 50 cases（ 42.7%） comorbided two or more etiological subtypes. The incidences of insomnia due to mental disorders， insomnia due to medical disorders， psychological physiology insomnia were 50（ 42.7%） ，41（ 35.0%） and 32（ 27.4%） respectively. Insomnia due to other sleep disorder were 33（ 28.2%）， 30 cases of which（ 25.6%） were for RLS. Compared with the CID-RLS group， CID+RLS group had insomnia more due to medical disorders （40.0% vs 12.6%， P=0.001）， CID+RLS group had insomnia less due to poor sleep hygiene， physiologic insomnia， and unspecified（ 3.3% vs 18.4%， P=0.044； 0% vs 13.8%， P=0.032）. Conclusions In the Neurological outpatients， nearly half comorbid two or more kinds of subtypes. It is more common to have insomnia due to mental disorders， medical disorders and psychological physiology insomnia among CID outpatients. The subtypes of two groups are significantly different.