Objective To evaluate disease progress and change in lymphocyte count (TLC), ratio of CD4⁺T(Th)to CD8⁺T(Tc)in peripheral blood in patients with coronavirus disease 2019 (COVID-19), and explore the feasibility of TLC and Th/Tc as monitoring indicator for progress of COVID-19. Methods Laboratory test data of 12 patients who were confirmed with COVID-19 in a hospital between January 28 and February 10, 2020 were collected, according to clinical symptoms, they were divided into severe/critical group and mild/common group, TLC in peripheral blood of two groups of patients was detected by flow cytometry, TLC and Th/Tc values of patients with different disease condition were compared. Results The proportion of TLC of COVID-19 patients was lower than the normal range, severe/critical group was lower than mild/common group; proportion of Th cell and Th/Tc of COVID-19 patients was higher than the normal range, severe/critical group was higher than mild/common group. Flow cytometry result showed that the absolute values of T lymphocyte, Th cell and Tc cell in two groups of patients all decreased, mild/common type group and severe/critical group was significantly different in absolute values of T lymphocyte ([913±275]μL vs[526±228]μL), Th cell ([530±99]μL vs[351±41]μL), and Tc cell ([255±84]μL vs[128±70]μL)(all P<0.05). Conclusion Judging the immune status and predicting inflammatory level of COVID-19 patients by TLC and Th/Tc can provide evidence for monitoring disease progress of COVID-19 and determining treatment opportunity for anti-cytokine storm.