Objective To explore the change of hung function in uremia patients before and after blood dialysis.Methods 45 uremia cases were tested with hung function before and after blood dialysis,inchuding FEV1?MMEF and V50.All data were analyzed with self contrast and related regression multianalysis.Result After blood dialysis,values of FEV1?MMEF and V50 are significantly higher than those before blood dialysis,the results are negative related with age and positive with height.Conclusion Lung function especial small airway is improved greatly after blood dialysis in uremia patients.Pay more attention to lung function during the blood dialysis treatment.