Conclusion
73.2% of convalescent COVID-19 patients are still positive for SARS-CoV-2 IgG. 35.93% patients have abnormal diffusion function and 37.5% patients have ground glass changes, especially in severe patients, 56.52% had diffusion dysfunction and 61.1% had ground glass changes of chest CT. Pulmonary function tests should be considered in recovered COVID-19 patients during the follow-up, particularly in the severe patients.