Objective To explore the characteristics of brain network changes in different subregions of the dorsolateral prefrontal cortex （DLPFC） in patients with chronic insomnia disorder （CID） accompanied by depressive disorder. Methods A total of 102 CID patients recruited from outpatient clinics of the Chengdu Second People's Hospital and neighboring community hospitals from January 2021 to June 2022 with 38 good sleep controls （GSC） were selected for the study. All subjects underwent comprehensive neuropsychological testing and MRI. Pittsburgh Sleep Quality Index （PSQI）， Self-Rating Depression Scale （SDS）， and Self-Rating Anxiety Scale （SAS） were used to assess participants' sleep quality， depression， and anxiety. During data preprocessing， 12 participants were excluded （10 of them were CID patients and 2 were GSC）. Based on SDS scores， 92 patients with CID were categorized into CID with depressive disorder group （CID-D group， SDS scores ≥ 53， n=36） and CID with non-depressive disorder group （CID-ND group， SDS scores ＜ 53，n=56）. Fourteen subregions of the DLPFC ［bilateral A9/46d， inferior frontal joint cortex （IFJ）， A46， A9/46v， A8vl， A6vl， A10l］ were selected from the Brainnetome brain atlas for the construction of a functional connectivity network of the DLPFC subregions based on seed points. A voxel-based analysis of variance （ANOVA） was used to compare the differences in the brain networks of the subregions of the DLPFC among the three groups. Pearson correlation was used to analyze the correlation between brain network characteristics of DLPFC subregions and depressive disorder and insomnia. Results There were no statistically significant differences between the three groups in terms of gender， age， and years of education （all P＞ 0.05）. PSQI， SAS and SDS scores were higher in CID-D and CID-ND groups than in GSC group， and the differences were statistically significant （all P ＜ 0.05）. There was no statistically significant difference between CID-D and CID-ND groups in terms of PSQI scores and duration of disease （all P ＞ 0.05）. One-way ANOVA showed that the differences in FC changes in different subregions of DLPFC were statistically significant among the three groups （P ＜ 0.05）. Among the 14 DLPFC subregions， there were differences in brain networks in 10 DLPFC subregions （bilateral A9/46d， bilateral IFJ， R.A46， bilateral A9/46v， L.A8vl， and bilateral A6vl）， of which， the DLPFC subregion networks that were elevated in patients in both CID-D group and CID-ND group， compared with those in GSC group， included R.A9/46d with right temporal middle gyrus， R.A46 with left middle temporal gyrus， L.A9/46v with left inferior frontal gyrus and left middle frontal gyrus， and R.A9/46v with bilateral middle temporal gyrus and bilateral superior temporal gyrus. The network of DLPFC subregions that were reduced in both CID-D and CIDND group patients included L.A9/46d with bilateral talar cortex， R.A46 with left inferior frontal gyrus and left middle frontal gyrus. Further analysis showed that compared with CID-ND group， the network of elevated DLPFC subregions in CID-D group included L.IFJ with the right middle temporal gyrus and right superior temporal gyrus， R.IFJ with the left postcentral gyrus， L.A6vl with the right superior temporal gyrus and the right middle temporal gyrus， and the network of reduced DLFPC subregions included R.A9/46d with the left crustal nucleus， left caudate nucleus， and left thalamus， and L.A9/46v with left inferior frontal gyrus， left middle frontal gyrus， and L.A8vl with left caudate nucleus， left shell nucleus and R.A6vl with bilateral caudate nuclei. Correlation analysis between FC of altered DLPFC subregions and depressive symptoms in patients in CID group showed that R.A9/46d （r=-0.30，P=0.003） was negatively associated with left chiasmatic nucleus， left caudate nucleus， and left thalamus， L.A8vl （r=-0.35，P ＜ 0.001） was negatively associated with left caudate nucleus and left chiasmatic nucleus， and R.A6vl （r=-0.28， P=0.008） was negatively associated with FC values in the bilateral caudate nucleus and SDS scores. L.IFJ （r=0.33， P=0.001） was positively correlated with right middle temporal gyrus and right superior temporal gyrus， and R.IFJ （r=0.33， P=0.001） was positively correlated with left postcentral gyrus， and L.A6vl （r=0.39， P＜ 0.001） was positively correlated with FC value of right superior temporal gyrus and right middle temporal gyrus， as well as SDS scores. Conclusions FC changes in the DLPFC subregion in patients with CID suggest that insomnia involves abnormal connectivity within regions of attention， emotion regulation， and memory processing