Background: Recent studies reported that sex differences in patients with coronavirus disease-2019 (COVID-19). However the predictive value of sex differences in disease severity were less studied by previous scholars. Methods: All adults (≥18 years) diagnosed with COVID-19 and admitted to Beijing Ditan Hospital, Capital Medical University (admission date from January 13 to March 19, 2020) were included in samples. Data analyzed in this study included epidemiological, demographic, comorbidities, initial symptoms and signs, laboratory findings, imaging study, disease severity and in-hospital mortality. Results: A total of 185 inpatients were enrolled in the study, among whom 95 patients are males (51.4%). The mean age of all patients was 41 years. Based on the hospital record, the duration from symptoms initiation to hospital admission was longer for men than that for women. Moreover, the mean BMI of males was relatively higher compared to females (25.45vs22.29, p<.001). In addition, the proportion of male patients with CHD, NAFLD, smoking and drinking history was higher than females. During the hospital stay, compared to female patients, male patients were more prone to develop symptoms such as high fever, cough, and chill. Higher levels of AST, CK, CRP and FIB were also observed in male patients. Following this fact, more patients with abnormal CT activities, severe and critical symptoms were developed in male group than females. However, there was no difference in complications and outcome between two groups. By analyzing data comprehensively, we found out that age (analyzed in quartiles, OR: 1.087; 95% CI: 1.038–1.139; p <.001) and BMI (OR: 1.250; 95% CI: 1.046–1.493; p =.014) could be used to help predict disease severity. Conclusions: In this cohort of hospitalized patients in Beijing, male patients developed more clinical symptoms, obtained more abnormal laboratory test results, and showed higher rates in severity of COVID-19. Other than that, the severity of COVID-19 was positively correlated with age and BMI independently.