In the Tungus-Manchu group, the endangerment of Manchu and Hezhe languages has been confirmed in the linguistic circles in China. Today, only aged people insome Manchu and Hezhe villages of Heilon^iang Province speak these two languages. This paper explores and analyzes the reasons for the endangerment of Manchu and Hezhe languages and provides evidence of the general rules of language endangerment. The research shows that social, psychological and linguistic factors work together to endanger the two languages. Their switch and variation modes have jointly endangered themselves, and the gradual and sudden changes in their linguistic systems have played a joint force. This paper is significant as a reference for further research into universal rules for the endangered languages.