OBJECTIVE: To investigate the clinical characteristics and CT imaging features of patients with different clinical types of coronavirus disease 2019 (COVID-19), so as to provide a reference for the treatment and evaluation of COVID-19. METHODS: The clinical data of 278 patients with COVID-19 admitted to Guangzhou Eighth People's Hospital from January 20th to February 10th in 2020 were collected. The patients were divided into mild, ordinary, severe and critical types. The differences of clinical symptoms and signs, laboratory examination indexes and CT image features of lung in different clinical types were analyzed and compared, and the relationship between clinical and imaging features and clinical types of diseases were analyzed. RESULTS: Among the 278 patients with COVID-19, 130 were male (46.8%) and 148 were female (53.2%), of whom 88.8% (247/278) were 20 to 69 years old. 238 (85.6%) patients combined one or more basic diseases. The source of cases was mainly imported cases (n = 201, 72.3%), of whom 89 cases were imported from Wuhan, accounting for 44.3% of all imported cases. With the aggravation of the disease, the male composition ratio, age and the number of basic diseases of patients gradually increased, and the incidences of fever, dry cough, chilly or chills, and fatigue in severe and critical patients were significantly higher than those in the mild and ordinary ones. The white blood cell count (WBC), neutrophil counts (NEU) and proportions (NEU%) of the severe and critical patients were higher than those of the mild and ordinary patients [WBC (x10(9)/L): 5.7+/-3.1, 6.5+/-2.4 vs. 5.4+/-1.7, 4.9+/-1.6; NEU (x10(9)/L): 4.4+/-3.1, 4.9+/-2.5 vs. 2.8+/-1.2, 2.9+/-1.3; NEU%: 0.72+/-0.13, 0.73+/-0.14 vs. 0.51+/-0.12, 0.59+/-0.11; all P < 0.01], while the lymphocyte count (LYM) and ratio (LYM%), platelet count (PLT) were lower than those in the mild and ordinary patients [LYM (x10(9)/L): 1.0+/-0.4, 1.2+/-0.8 vs. 2.1+/-0.9, 1.5+/-0.6; LYM%: 0.21+/-0.11, 0.20+/-0.12 vs. 0.40+/-0.11, 0.32+/-0.11; PLT (x10(9)/L): 177.1+/-47.8, 157.7+/-51.6 vs. 215.3+/-59.7, 191.8+/-64.3; all P < 0.05]. The level of albumin (Alb) was the lowest in the critical patients and the level of total bilirubin (TBil) was the highest, which was statistically significant as compared with the mild, ordinary and severe patients [Alb (g/L): 33.0+/-5.8 vs. 42.8+/-4.4, 39.6+/-5.1, 34.4+/-4.2; TBil (mumol/L): 20.1+/-12.8 vs. 12.0+/-8.7, 10.9+/-6.3, 12.2+/-8.3; both P < 0.01]. Lactate dehydration (LDH) and cardiac troponin I (cTnI) in the severe and critical patients were significantly higher than those in the mild and ordinary patients [LDH (mumolxs(-1)xL(-1)): 5.6+/-2.2, 5.0+/-2.9 vs. 2.8+/-0.9, 3.3+/-1.2; cTnI (mug/L): 0.010 (0.006, 0.012), 0.010 (0.006, 0.012) vs. 0.005 (0.003, 0.006), 0.005 (0.001, 0.008); both P < 0.05]. C-reactive protein (CRP) level of severe patients were higher than that in the mild, ordinary and critical patients [mg/L: 43.3 (33.2, 72.1) vs. 22.1 (16.2, 25.7), 29.7 (19.8, 43.1), 25.8 (23.0, 36.7), P < 0.01]. The level of procalcitonin (PCT) in the severe and critical patients was higher than that in the mild and ordinary patients [mug/L: 0.17 (0.12, 0.26), 0.13 (0.09, 0.24) vs. 0.06 (0.05, 0.08), 0.05 (0.04, 0.09), P < 0.01]. The typical CT imaging features were as follows: the ordinary type mainly showed the single or multiple ground glass shadows on the chest image; the severe type mainly showed the multiple ground glass shadows, infiltration shadows or solid transformation shadows. Compared with the ordinary patients, the lesions increase, and the scope of the lesion expanded to show double lungs. Critical type was mainly manifested as diffuse consolidation of both lungs with multiple patchy density increase shadows, multiple leafy patchy density increase shadows were seen on each leaf, most of them were ground glass-like density, and some were shown separately lung consolidation. CONCLUSIONS: Men, advanced aged, and combining multiple underlying diseases are high-risk populations of COVID-19, and they should pay close attention to the risk of progressing to severe or critical type. CT imaging features could be used as an important supplement when diagnosing severe and critical COVID-19.