In the past 4 decades of reform and opening up, the motivation of college students to join the Party has undergone a complicated evolution of monism, dualism and pluralism. Although the mainstream of current college students' motivation to join the Party is correct, we must also face the objective reality of the decline of faith and the rise of utilitarian motive. In the course of the evolution of college students' motivation to join the Party, the change of the times is the main factor, the Party's image is the key factor, and the individual "three views" are the core factors. The experience and reasons of the 4 decades ‘college students’ motivation evolution show that, we should stick to "three-points awareness" to defend the good image of the Party in the minds of college students, adhere to "three-causes idea" to ensure the effectiveness of motivation education, integrate "three classes" to realize the systematization of motivation education, and explore "three-tests evaluation" to gradually improve the scientific evaluation of college students' motivation to join the Party.