Objective To explore the rule of etiopathogenisis disposition and tendency.Methods Bronchoscopic test was performed in these 899 patients.The differences among different periods,age groups and smoking status groups were compared.Results In recent 15 years,the ratio of old patients raised obviously.The causes were unspecialized inflammation(76.6%),tumor(12.9%),and tuberculosis(8.2%).Unspecialized inflammation cause was significantly more in young group than middle age group and old age group(P400 cigarette-years group than non-smoker group(P400 cigarette-years,should be alert for tumor,and take bronchoscopic test timely.Young patients should pay more attention to tuberculosis cause.