Objective:To compare and discuss the GOLD and the diagnostic criteria of severity of COPD adopted by Chinese respiratory academy in 1997 and 2002. Method:The data of pulmonary function of 713 COPD from 1991 to 2001were reviewed by t - test. All patients were classified as mild ,moderate and severe COPD by the diagnostic criteria of Chinese respiratory academy in 1997 and traditional criteria of pulmonary dysfunction . Some associated problems were discussed. Results:The data and results matched with the two criteria, but data of FEV1/FVC in mild COPD group were different from the diagnostic criteria of GOLD and Chinese respiratory academy in 2002.Conclusion:Chronic bronchitis without airflow limitation is included in the concept of COPD by GOLD and Chinese respiratory academy's diagnostic criteria in 2002,so this part of patients may not be delayed in diagnosis. But FEV1/FVC of some mild COPD patients in early stage may not be lower than 70 %, these COPD patients may be misdiag nosed which is unfavorable to the early intervention and treatment of COPD . In addition , the range of moderate COPD in the criteria of GOLD is too wide to differentiate the severity of the disease,so it is not convenient for guiding the rehabilitative treatment. The functional examination of respiratory muscles will differentiate whether the airflow limitation is from the airway or from the dysfunction of respiratory muscles, and it is irreplaceable for guiding the rehabilitative treatment of respiratory muscles and evaluating the efficiency. We suggest more attention should be paid to these probloms.