Objective：Investigating the clinical value of lung ultrasound (LUS), chest radiographs and laboratory indices in predicting the prognosis of critically ill patients with COVID-19.Method: Sixty-three COVID-19 critically ill patients admitted to the intensive care unit of the Affiliated Hospital of Guizhou Medical University were selected, and bedside LUS examination (8-zone) and LUS score were performed after admission, and bedside chest radiography and chest radiography score were performed 48h before and after ultrasonography. The patients' clinical data and laboratory indexes were collected, and the patients were divided into the death group and the survival group according to their prognosis, and the correlation between the LUS scores, chest radiograph scores, and laboratory indexes and prognosis of the two groups was analysed, and the ROC curves were drawn to analyse the value of LUS scores, chest radiograph scores, LUS combined with chest radiographs, and LUS combined with Pco2 in the prognostic prediction of patients with the critically ill type of COVID-19.Results:Leukocyte count and Pco2 were higher in the death group than in the survival group, Spo2 and PH were lower than in the survival group, and LUS and chest film scores were higher than in the survival group, and the differences were statistically significant (p<0.05); the results of the one-way logistic regression showed that an increase in LUS and chest film scores would increase the risk of death of the patients (OR=1.22, p=0.010/OR=1.31, and p=0.010); the subjects' working curve (ROC curve) showed that the area under the curve for LUS and chest radiograph scores alone to assess the prognosis of COVID-19 critically ill patients were 0.708 and 0.696, respectively, and ultrasound was slightly better than chest radiograph. The area under the curve for the combined assessment of the two was 0.725, which was superior to that of the separate assessment.LUS combined with Pco2 had the best assessment efficacy, with an area under the curve of 0.790.Conclusions:The 8-zone LUS score was slightly better than the chest radiograph score in assessing the prognosis of critically ill patients with COVID-19, and the combination of the two was better than the separate assessments, with the best efficacy of the LUS score in combination with Pco2.