Objective To investigate the alterations of the amplitude of low frequency fluctuation (ALFF) by the resting-state fMRI in first-episode major depressive disorder (MDD) patients, and to analyze the relationship between brain area of different ALFF alterations with their aggressive behaviors. Methods Thirty first-episode MDD patients receiving no treatment or stopping treatment for 2 weeks and 30 sex-, age-, and education-matched healthy controls were included in this study. All the participants were scanned with 3.0 T resting-state fMRI scanner and the blood oxygenation level dependent (BOLD) signals were acquired to calculate the amplitude of low frequency fluctuation (ALFF). Then we examined the differences in ALFF findings between the two groups and the correlations between the scores of aggressive behavior and ALFF in the brain areas showing significant group differences. Results Our results showed that MDD patients had significantly increased ALFF in the left insula, parietal lobe sub-gyral, precentral gyrus, and the right superior temporal gyrus, precentral gyrus, and inferior frontal gyrus compared with the health controls (P<0.001, corrected by Alphasim); while they had decreased ALFF in the left thalamus, precuneus and right lingual gyrus, and fusiform gyrus (P<0.001, corrected by Alphasim). The correlation analysis indicated that the increased ALFF in the left precentral gyrus was positively correlated with the scores of physical aggression, self-aggression, and total score of aggressive behaviors (r=0.41, 0.49, 0.39, P<0.05 or 0.01). The increased ALFF in the right inferior frontal gyrus was negatively correlated with anger (r=-0.44, P<0.05). Conclusion Spontaneous abnormal neural activities exist in some brain regions of MDD patients in the resting-state fMRI, and the increase of ALFF in regions of frontal is closely related to the aggressive behaviors of patients.