Objective To investigate the abnormality of the cingulate-precuneus functional connection in the first-episode depressive disorder patients and their first-degree relatives. Methods From June 2016 to February 2018， 23 patients with first-episode untreated depressive disorder， 17 first-degree relatives without depressive disorder and 28 healthy people without family history were examined by resting-state functional magnetic resonance imaging（ fMRI）. HAMD-24 was used to assess the severity of the illness. Results There were differences in functional connectivity between the cingulate gyrus and the left and right precuneus among the three groups of subjects. Compared with healthy controls， the functional connectivity of the left anterior cuneal lobe was increased in the first-degree relatives， and the functional connectivity of the left and right anterior cuneal lobe was increased in the patient group. Compared with the first-degree relatives group， the functional connectivity increased significantly in the right precuneus in the patient group. Partial correlation analysis revealed that the cingulate-precuneus functional connection was positively related to the severity of the depressive disorder（ r=0.493， P=0.027）. Conclusions The onset of the depressive disorder is related to the increase of functional connectivity between the cingulum and the precuneus， which is related to the severity of the disease. The cingulate-left precuneus functional connectivity may be a possible genetic pathological mechanism.