Objective:To explore the brain structural changes in patients with post-traumatic stress disorder (PTSD) after traffic accident.Methods:Forty-six patients with PTSD (PTSD group) who received treatment in Psychology Department, Second People's Hospital of Guangdong Province from January 2021 to June 2022 after traffic accidents and 49 gender- and age-matched normal healthy subjects (control group) were selected; all subjects underwent MRI 3D-T1WI structural imaging of the whole brain. Voxel-based morphometry (VBM) was used to detect the volume differences of the gray matter between the two groups. The correlations of volumes of the gray matter in PTSD group which was different from that in the control group with Clinician-Administered PTSD Scale (CAPS), PTSD Checklist-Civilian Version (PCL-C) and Hamilton Rating Scale for Depression (HAMD) were analyzed.Results:Compared with control group, patients in PTSD group had significantly decreased gray matter volumes in the left hippocampus, left postcentral gyrus and right superior frontal gyrus ( P<0.001, adjusted GRF); no regions with increased gray matter volumes were noted. The gray matter volume in the left postcentral gyrus was negatively correlated with CAPS scores in PTSD patients ( r=-0.443, P=0.002); the gray matter volumes in other brain regions with differences were not correlated with CAPS, PCL-C or HAMD scores ( P>0.05). Conclusion:Structural changes of the left hippocampus, left postcentral gyrus and right superior frontal gyrus are observed in PTSD patients caused by traffic accidents, and the gray matter volume of left postcentral gyrus is related to severity of PTSD clinical symptoms.