Objective To investigate the spontaneous activity of brain neurons in patients with obsessive－compulsive disorder (OCD) under resting state. Methods Forty－eight OCD patients and 50 age－, gender－ and year of education－matched normal controls were enrolled. All the subjects underwent 3.0 T fMRI to acquire resting state brain image. The brain regions with significant differences in amplitude of low－frequency fluctuation (ALFF) between patients and controls were analyzed. Whole－brain functional connectivity (FC) were analyzed using the brain regions with significant differences as seed points, and the correlation between brain regions with significant differences in ALFF and FC analysis and obsessive－compulsive symptoms was analyzed. Results Compared to the control group, the ALFF of left dorsolateral prefrontal cortex increased in patients with OCD (t=4.305, P＜0.001). Compared to the controls, the analysis of whole－brain FC (based on MNI template) with the left dorsolateral prefrontal cortex as the regions of interest showed that the FC strength between the left dorsolateral prefrontal cortex and right orbital inferior frontal cortex (t=3.897, P＜0.001), left anterior cingulate cortex (t=3.370, P＜0.001), right anterior cingulate cortex (t=4.299, P＜0.001), left middle cingulate cortex (t=3.220, P＜0.001), right middle cingulate cortex (t=4.607, P＜0.001) enhanced; the FC strength between the left dorsolateral prefrontal cortex and the left opercular part of inferior frontal gyrus (t=－4.630, P＜0.001) weakened in patients with OCD. The FC between the left dorsolateral prefrontal cortex and the left opercular part of inferior frontal gyrus was negatively correlated with obsessions score(r=－0.369, P=0.014), compulsions score (r=－0.392, P=0.009) and total score (r=－0.393, P=0.008) of the Yale－Brown obsessive compulsive scale (Y－BOCS). Conclusion In patients with OCD, spontaneous neural activity of the left dorsolateral prefrontal cortex is enhanced in resting state, and the FC with multiple brain regions is abnormal. The FC strength between the left dorsolateral prefrontal cortex and the left opercular part of inferior frontal gyrus is associated with obsessive－compulsive symptoms.