GeneXpert MTB/RIF can quickly detect Mycobacterium tuberculosis and whether it is a drug-resistant strain to provide doctors with accurate medication treatment and prevention. This case presented to the doctor due to urogenital discomfort. The chest radiography(CXR) during hospitalization revealed an abnormality. The sputum acid fast staining in the laboratory was positive, and the sputum and urine samples were sent for GeneXpert MTB/RIF. It is positive for MTB and resistant to Rifampin (RIF). But it is found that Rifampin (RIF) is sensitive through gold standard LJ proportion drug susceptibility (LJ-DST). After further genetic analysis, it was found that the gene rpoB had silent mutation P520P (silent mutation P520P), so the susceptibility of rifampin was judged to be sensitive. This similar genomic mutation cases are really rare and there were only 8 cases reported in Taiwan.  (J Intern Med Taiwan 2021; 32: 356-362)