Background: A rapid outbreak of novel coronavirus, COVID-19, made it a global pandemic. This study focused on the possible association between lymphopenia and Computed tomography (CT) scan features and COVID-19 patient mortality. Method: The clinical data of 596 COVID-19 patients were collected from February 2020 to September 2020. The patients’ serological survey and CT scan features were retrospectively explored. Results: The median age of the patients was 56.7±16.4 years old. Lung involvement was more than 50% in 214 COVID-19 patients (35.9%). The average blood lymphocyte percentage was 20.35 ±10.16. The levels of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and platelet-to-lymphocyte ratio (PLR) may not indicate the severity and prognosis of COVID-19. Patients with severe lung involvement and lymphopenia were found to be significantly associated with increased odds of death (odds ratio [OR], 9.24; 95% confidence interval [95 CI%], 4.32- 19.78). These results indicated that lymphopenia <20% along with pulmonary involvement >50% impose a multiplicative effect on the risk of mortality. The in-hospital mortality rate of this group was significantly higher than other COVID-19 hospitalized cases. Furthermore, they meaningfully experienced a prolonged stay in the hospital (P= 0.00). Conclusion: The Lymphocyte count less than 20% and chest CT scan findings with more than 50% involvement might be related to the patient’s mortality. It could act as laboratory and clinical indicators of disease severity and mortality.