Backgound: To investigate the right heart function in COVID-19 (coronavirus disease 2019) patients with acute respiratory distress syndrome (ARDS). Methods: A retrospective analysis of 49 COVID-19 patients with ARDS was performed. Patients were divided into severe and critically severe group according to severity of illness. Age-matched healthy volunteers were recruited serving as a control group. The cardiac cavity diameters, tricuspid annular plane systolic excursion (TAPSE), tricuspid valve regurgitation pressure gradient biggest (TRPG), pulmonary arterial systolic pressure (PASP), maximum inferior vena cava diameter (IVCmax) and minimum diameter (IVCmin), and inferior vena cava collapse index (ICV-CI) were measured using echocardiography. Results: We found the TAPSE was significantly decreased in pneumonia patients compared to healthy subjects (P<0.0001), which was significantly lower in critically severe patients (P=0.0068). TAPSE was less than 17mm in 3 (8.6%) severe and 5 (35.7%) critically severe patients. There were no significant differences in PASP and TRPG between severe and critically severe patients. The IVCmax and IVCmin were significantly increased in critically severe patients compared to healthy subjects and severe patients (P < 0.01), whereas ICV-CI was significantly decreased (P < 0.05). COVID-19 patients had significantly larger right atrium and ventricle than healthy controls (P < 0.01). The left ventricular ejection fraction (LVEF) in critically severe patients was significantly lower than that in severe patients and healthy controls (P < 0.05). Conclusion: Right ventricular function is impaired in critically severe COVID-19 patients. The assessment and protection of the right heart function in COVID-19 patients should be strengthened.