Objective: To explore the correlation between depression severity and neurocognitive function in patients with late-onset depression . Methods: The patients with late-onset depression treated in Jinhua Second hospital from February 2015 to December 2017 were assigned into the mild,moderate and severe groups according to the severity of depression assessed by the Hamilton Depression Scale-17（HAMD-17）. At the same time,some healthy persons were selected as the control group. Wisconsin Card Sorting Test（WCST）,Verbal Fluency Test（VFT）and Stroop Test were carried out,and the scores of these tests were compared in the four groups. The correlations of WCST, VFT, Stroop Test and HAMD-17 scores were analyzed . Results: There were 32,28,35 and 35 subjects involved in the mild,moderate,severe and control group,respectively. The subjects of the mild group,moderate group and severe group had more total errors,perseverative responses and perseverative errors than the control group,and less percent conceptual level responses than the control group （all P<0.05）. The total errors,perseverative responses,perseverative errors and percent perseverative errors increased and the percent conceptual level responses decreased gradually with the severity of depression（all P<0.05）. The correct numbers of Stroop-consistent group and VFT in the severe group were less than those in the control,mild and moderate group（all P<0.05）,which was significantly different between the mild,moderate and control group （P>0.05）. The HAMD-17 scores were negatively correlated with the correct numbers of Stroop congruent group（r=-0.448,P<0.001）and VFT（r=-0.401,P<0.001）,and were positively correlated with perseverative responses in the WCST（r=0.784,P<0.001） . Conclusion The neurocognitive impairment in patients with late-onset depression aggravated with the severity of depression.