Tuberculous destroyed lung (TDL) is diagnosed by a clear past history of tuberculosis with findings of parenchymal destruction verified by chest X-ray. Despite the resultant deterioration of lung function and quality of lives seen in TDL patients, the exact mechanism or characteristics of pulmonary function worsening have not been clearly studied. We investigated the feature of respiratory impairment of TDL patients, and studied whether extent of destroyed lung measured with chest CT has any correlation with routine lung function. To evaluate the degree of destruction, the Goddard classification scoring system was modified into a novel scoring system (destroyed lung score, (DLS)) with a score from 0 to 4. Twenty-five subjects were enrolled. TDL predominantly manifested as an obstructive pattern (64%, 16/25). Median value of DLS of the entire lung was 2.6 (1.7-3.9). Absolute values of FEV1 and FVC were both negatively associated with DLS (r = -0.78, P = 0.001, and r = -0.61, P = 0.021). Percentage of predicted value of FEV₁ and FVC were also negatively associated with DLS (r = -0.62, P = 0.019, and r = -0.76, P = 0.002). Our study shows that lung function of TDL patients were notably correlated with the extent of destroyed lung measured with chest CT scan.