Abstract: Objective To detect the lymphocyte subsets in peripheral blood and explore the clinical value of lymphocyte subsets in the diagnosis of rheumatoid arthritis. Methods Patients with rheumatoid arthritis who were admitted into Xuzhou Traditional Chinese Medicine Hospital from January 2019 to October 2020 were enrolled and their clinical data were retrospectively analyzed. They were divided into two groups: a rheumatoid arthritis group (n=40) and a control group (n=33). Their peripheral lymphocyte subsets were detected, so as to plot a receiver operating characteristic (ROC) curve for analysis of the diagnostic efficiency. Results The rheumatoid arthritis group produced remarkable decreases in the total T lymphocyte CD3⁺ absolute count, helper/induced CD4⁺ T lymphocyte absolute count, inhibiting/killer CD8⁺ T lymphocyte absolute count, and CD16⁺ CD56⁺ NK lymphocytes absolute count, compared with the control group (P<0.05), with the area under the ROC curve (AUC) were 0.953, 0.833, 0.788, and 0.617. The optimal diagnosis efficiency was found for T lymphocyte absolute count. There was no significant difference in the absolute count of CD19⁺ in B lymphocytes compared with the control group (P>0.05). Conclusions The absolute counts of T lymphocyte CD3⁺, helper/inducer T lymphocyte CD4⁺, inhibitory/killer T lymphocyte CD8⁺ and NK lymphocyte CD16⁺CD56⁺ have good diagnostic efficacy, which is of predictive significance for the diagnosis of rheumatoid arthritis.