In the 1970s,Premier Zhou Enlai first proposed,"when possible,we will achieve the liberation of Taiwan by peaceful means",and proposed the idea of the third KMT-CPC cooperation.Whether KMT-CPC cooperation can be achieved requires to analyze the obstacles,from the basic principles of Marxism,the internal decides the external,the external works through the internal,this paper analyzes the difficulties from the internal and external reasons of the third collaboration between the two parties.