Tuberculosis (TB) is one of the three major infectious diseases in China and all over the world. In 2014, for the first time, TB killed more people than HIV did. Non-first line anti-TB drugs are used as main drugs in the treatment of MDR-TB. However, MDR-TB can gradually develop as extensively drug-resistant TB (XDR-TB) because of poor diagnosis, the unreasonable treatment, poor medical conditions and so on. The death rate of XDR-TB is close to lung cancer. Research on the mechanism of drug resistance of Mycobacterium tuberculosis has turned to non first-line anti-TB drugs: second and third line drugs and some new anti-TB drugs in development. In this review, we summarized the drug resistance mechanisms of the common non-first line anti-TB drugs. Most of drug resistant TB patients can't get timely diagnosis and correct treatment. So at the end of this article, we also summarized the common methods to diagnose drug-resistant TB.