Objective: To study the relationship between the polymorphism of drug resistant gene rpoB and drug resistance against rifampicin(RFP) of M. tuberculosis L-forms, and to evaluate its clinical application. Methods: A total of 52 clinical isolated strains of M. tuberculosis L-forms were collected. rpoB gene polymorphism was analyzed by polymerasc chain reaction and single-strand conformation polymorphism (PCR-SSCP) and conventional antimicrobial susceptibility test (AST). Their results were compared. Results: AST results showed that 38 of 52 clinical isolated strains were drug resistance (73. 08%), while PCR-SSCP indicated 65. 38% (32/52) rpoB gene polymorphism. There was no statistic significance (X2 = 2. 4914) between the 2 methods. Conclusion:Combined the application of PCR-SSCP with AST in detecting rpoB drug resistant gene polymorphism of M. tuberculosis L-form from pneumoconiosis patients with tuberculosis may have advantages at earlier diagnosis and guidance of clinical medications. Objective: To study the relationship between the polymorphism of drug-resistant gene rpoB and drug resistance against rifampicin (RFP) of M. tuberculosis L-forms, and to evaluate its clinical application. Methods: A total of 52 clinical isolated of M. tuberculosis L-forms were collected. RpoB gene polymorphism was analyzed by polymerasc chain reaction and single-strand conformation polymorphism (PCR-SSCP) and conventional antimicrobial susceptibility test (AST). Their results were compared. Results: AST results showed that 38 of 52 clinical while was PCR-SSCP indicated 65. 38% (32/52) rpoB gene polymorphism. There was no statistic significance (X2 = 2.4914) between the two methods. Conclusion: Combined the application of PCR-SSCP with AST in detecting rpoB drug-resistant gene polymorphism of M. tuberculosis L-form from pneumoconiosis patients with tuberculosis may have advantages at earlier diagnosis and guidance of clinical medications .