Background: Rare studies have been done about rehabilitation stage in patients with COVID-19. Materials and Methods: In randomized controlled clinical trial, thirty Participants were randomly divided to control group (CG) and intervention group (IG). Participants in IG group performed rehabilitation trainings 30 minutes once a day for two 4 weeks. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV1/FVC and forced expiratory flow (FEF) 25-75% were measured using spirometry. Six-min walk distance [6-MW) test as well as heart rate (HR) and blood oxygen saturation (SPO2) were measured, also. Results: Twenty-eight patients completed the study. FVCact, FEV1act, FEV1pred, FEV1/FVCact, FEV1/FVCPred were significantly improved in intervention group as compared to control group (Ptime*group FVCact= 0. 01, Ptime*group FEV1act< 0. 001, Ptime*group FEV1pred< 0. 001, Ptime*group FEV1/FVCact= 0. 01, Ptime*group FEV1/FVCpred< 0. 01). In addition, changes in FVCpred and PEFact became significant after the adjustments [Ptime*group FVCpred= 0. 03, Ptime*group PEFact= 0. 05). Finally, no significant differences were seen in changes of rest heart rate (RHR) (Ptime*group: 0. 55), walk heart rate (WHR) (Ptime*group: 0. 61), walked distance (Ptime*group: 0. 41), and PEFpred [Ptime*group= 0. 09) throughout the study between the two groups. Conclusion: This study illustrated rehabilitation training significantly increased FVC, FEV1, FEV1/FVC, and PEFact, while it had no significant influence on PEFpred, RHR, WHR and walk distance after 8-weeks. However, further RCTs are needed to confirm our findings.