Objective To explore the changes of olfactory function in depression before and after treatment， and to preliminarily explore the correlation between olfactory function and depression severity， inhibition control and emotional response. Methods A total of 35 patients with unipolar onset depression in Shanghai Yangpu Mental Health Center and Jiading Central Hospital from January 2017 to August 2018 were selected as depression group， and 33 healthy adults matched with depression group in gender， age and education level were selected as healthy control group. 17-item Hamilton Depression Rating Scale（ HAMD-17）， Hamilton Anxiety Rating Scale（ HAMA）， Chinese Smell Identification Test（ CSIT） and emotional Stroop test （EST） were applied to evaluated the levels of depression， anxiety， olfactory and the response time of Stroop task under emotional interference， at the baseline before treatment and follow-up 3 months after treatment. SPSS 17.0 software was used to analyze and process the data. Multiple linear regression analysis was used to analyze the correlation between age， HAMD-17， HAMA， emotional Stroop task response time at baseline and olfactory test results. Results At baseline， the total CSIT score of the depression group was lower than that of the control group at baseline［ 7（ 6， 9） vs 9（ 8， 9）， P ＜ 0.001］， while there was no statistically significant difference between the two groups 3 months after treatment［ 8（ 8， 9） vs 9（ 8， 9）， P=0.22］. At baseline， the mean response time（ MRT） of emotional Stroop test in depression group was higher than that in healthy control group（ P＜0.001）. There were no statistically significant differences in POS-C［ （539.0±109.0） ms vs（ 489.7±132.1） ms］ and POS-I［ （538.1±98.2） ms vs（ 494.7±135.3） ms］ between the two groups（ P=0.10， 0.13） at follow-up. At the same time， the differences in NEG-C［ （573.0±149.2） ms vs（ 474.8±111.7） ms］， NEG-I［ （530.9±112.7） ms vs（ 474.9±94.0） ms］ and NEU［ （532.2±114.0） ms vs（ 476.2±101.5） ms］ between the two groups were statistically significant（ t=3.06，2.22，2.14；P ＜ 0.01）， prompting the results were still longer than those of the control group. The final regression model obtained by the multiple linear regression analysis had included two independent variables with age and NEG-C （F=10.811， adjusted R2=0.366，P ＜ 0.05） at baseline level of depression. Conclusions The patients with depression have olfactory function and inhibition and control function damage during the attack period， and it will improve with the improvement of the disease. The result of multiple linear regression suggested that in addition to age， the inhibitory control function might be the key influencing factor of the olfactory function， rather than the emotional severity assessed by the scales（ HAMD-17 and HAMA）.