Objective To investigate the correlation between plasma cortisol level and cognitive function in depression patients with somatic symptoms. Methods A total of 93 patients with first-episode mild and moderate depression admitted to Tangshan Kailuan Mental Health Center from November 2021 to July 2022 were selected as the research objects. All the patients were assessed by Health Questionnaire-15 （PHQ-15）. Patients with a score equals or over 10 were assigned to somatic symptoms depression group （n=53）， while patients with a score less than 5 were assigned to non-somatic symptoms depression group （n=40）. The 24-item Hamilton Depression Scale （HAMD-24） and Montreal Cognitive Assessment Scale （MoCA） were used to compare the degree of depression and cognitive function of the two groups of patients. The cortisol levels of the two groups were measured by ELISA at 8 am. Pearson correlation analysis was used to analyze the correlation between HAMD-24， MoCA score and plasma cortisol level in two groups of patients. Results The total score of HAMD- 24 in somatic symptoms depression group was （35.92±3.28）， which is higher than that in non-somatic symptoms depression group （31.78±1.70）， and the difference was statistically significant （P＜ 0.05）. The scores of MoCA total score， attention， delayed recall and orientation dimension in non-somatic symptoms depression group were higher than those in somatic symptoms depression group ［（25.38±2.50） vs （23.98±3.58）， （5.00±0.64） vs （4.57±1.14）， （3.65±0.66） vs （3.21±0.79）， 6.00（5.00，6.00） vs 6.00（6.00，6.00）］， and the differences were statistically significant （P ＜ 0.05）. The plasma cortisol level in somatic symptoms depression group was （21.76±5.50） μg/dl， higher than that in non-somatic symptoms depression （15.34±4.95） μg/dl， and the difference was statistically significant （P＜ 0.01）. The correlation analysis showed that the plasma cortisol level in somatic symptoms depression group was positively correlated with the total score of HAMD-24， and negatively correlated with the total score of MoCA and the scores of attention， delayed recall and orientation dimensions （r=0.550，-0.452，-0.474，-0.513，-0.489；P ＜ 0.01）. Conclusions The depression degree of depression patients with somatic symptoms is severe and the plasma cortisol level is high， and the plasma cortisol level is correlated with cognitive function.