Objective To study the characteristics and differences of the amplitude of low-frequency fluctuation (ALFF) and the fractional ALFF (fALFF) of the major disorder depression (MDD) and their first-degree relatives in the resting state by functional magnetic resonance imaging (fMRI),to understand the early brain function in patients with MDD.Methods 3.0T fMRI in the resting state was performed in 10 patients with MDD (the depression group),10 first-degree relatives of MDD (the first-degree relatives group) and 10 healthy volunteers (the control group).A statistics analysis of ALFF and fALFF were performed subsequently.Results The ALFF and fALFF values measured in left cerebellum, left precuneus and left medial prefrontal cortex of MDD group were significantly lower than those of the first-degree relatives group (P<0.05).The ALFF values measured in right posterior cingulate cortex and right superior parietal lobule of MDD group were significantly lower than those of the first-degree relatives group (P<0.05).The ALFF and fALFF values measured in left cerebellum, left precuneus and left superior parietal lobule of MDD group were significantly lower than those of the control group (P<0.05).The ALFF values measured in right cingulate cortex and medial prefrontal cortex of MDD group were significantly lower than those of the control group (P<0.05).There was no significance difference found in ALFF values between the first-degree relatives group and the control group,the fALFF values measured in left superior parietallobule of the first-degree relatives group were significantly lower than those of the control group (P<0.05).Conclusion As the widespread ALFF, fALFF abnormalities of brain in MDD and first-degree relatives of MDD,a hypothesis can be get that these abnormal brain region may be associated with cognitive network disorders and emotional distress in MDD.