Objective To explore the morphological changes of gray matter in patients with olfactory dysfunction following upper respiratory tract infections, and obtain the imaging characteristics of olfactory center structure in patients with post-infectious olfactory dysfunction.Methods Twenty-four patients with post-infectious olfactory dysfunction (OD group) and 20 healthy subjects (control group) with normal olfactory function were selected. Voxel-based cortical morphometry was used to compare the volume of gray matter and white matter between the two groups.Results Of the OD group, the total ordor threshold, discrimination and identification (TDI) score was 16.45±5.62, while the threshold (T) score was 2.33±0.93, the discrimination (D) score was 6.54±2.60, and the identification (I) score was 7.58±3.22, the average duration of olfactory dysfunction was (19.00±6.33) months, and the visual analogue scale (VAS) score was 7.79±2.41. The differences of above-mentioned indexes between the OD group and the control group were all statistically significant (P<0.05). The total gray matter volume and olfactory cortex volume of the OD group were significantly smaller than those of the control group (P<0.05). The proportion of total gray matter volume to total brain volume and cortical thickness were positively correlated with olfactory function TDI score (r=0.71, P<0.0001; r=0.69, P=0.0009).Conclusion Patients with post-infectious olfactory dysfunction have decreased gray matter volume and olfactory cortex volume, and olfactory function is positively correlated with gray matter volume ratio and cortical thickness.