Objective：To investigate the relationship between laboratory examination indexes and disease severity of coronavirus dis－ease 2019（COVID-19），and to find out the risk factors for the severe pneumonia. Methods：Eighty-one cases of COVID-19 admitted to the isolation ward of the third people’s Hospital in Ezhou City，Hubei Province，including 49 common cases and 32 severe cases were collected and analyzed statistically in terms of age，gender，chronic basic diseases，and clinical laboratory examination indexes of the two groups and the receiver operating characteristic（ROC） curve was used to evaluate the predictive value of the examination in－dexes. Results：Among the 81 cases，the age of the common group was （49.86±13.79） years old，that the age of the severe group was （62.84±13.26） years old，and the age of severe group was older than that of common group（P<0.05）. Patients complicated with higher values of chronic basic diseases，white blood cell count（WBC），neutrophil count（NEU），NEU percentage，C-reactive protein（CRP），total bilirubin（TBIL），creatine kinase（CK），and lactate dehydrogenase（LDH） were more likely to develop severe pneumonia（P<0.05）. At the same time，the lower the lymphocyte count（LYM），LYM percentage and albumin values of COVID-19 patients were al－so prone to severe patients（P<0.05）. After anti-infection and anti-virus treatment，the above indexes gradually returned to normal. To predict the risk of severe COVID-19 patients，the area under the receiver-operating characteristic curve（AUC） of age，WBC，NEU，NEU%，LYM，LYM%，ALB，CRP and LDH were 0.757，0.711，0.783，0.904，0.850，0.921，0.754，0.848 and 0.807 respectively. Repeated measurement analysis of variance showed that there was significant interaction between different condition groups of NEU%，LYM%，CRP，LDH and treatment time. Conclusion：Older COVID-19 patients with chronic diseases are more likely to develop severe pneumonia. Clinically，WBC，NEU，NEU%，LYM，LYM%，ALB，CRP and LDH can be used to assess the severity of COVID-19. Especially，NEU%，LYM% combined with the age of patients and the CT manifestations of lung can be used to predict the risk of progression from common patient to severe patient，so as to adjust the treatment plan in time.