The credit system is a teaching management system that measures the amount of students' learning by credits. It has been accepted by most countries and is constantly improving and developing. Credit system is the product of productivity development, science and technology and social progress. Eliot, president of Harvard University in the United States, believes that people's ability, quality and other differences can not be cultivated according to the same rigid model, advocating the expansion of curriculum subjects, allowing students to have a full range of choices, and arrange their own learning majors and courses. The new problem encountered in the flourishing of elective course system is how to calculate the amount of study that students must complete to obtain a degree after graduation, so the credit system comes into being. The credit system was born in Harvard University in 1872, and then gradually promoted and improved. Compared with the academic year, the credit system in the general sense has the following advantages: (1) the flexibility of the learning time limit. It refers to the number of years required by academic education, but it is not strictly limited by the number of years, students can take full credits and graduate in advance; You can also graduate with a lag time. From the perspective of educational economics, the effective and individualized allocation of educational time can reduce the cost of products and improve the efficiency of education, which is beneficial to both individuals and society. (2) The selectivity of learning content. To a certain extent, it allows students to choose the courses and majors that they think are necessary and interesting, which is its essence. A \"credit system\" without elective rights cannot be considered a credit system. (3) The flexibility of curriculum investigation. For courses taken by students, if they fail the exam, they can take the exam again or take another exam until they have passed and obtained the equivalent credit. This allows the educatees to adjust themselves according to their own development within a certain limit, which not only reflects the importance of credits, but also helps students to form talents to meet the needs of society. (4) Guidance of the training process. The credit system has created the necessary conditions for students to independently and freely arrange their studies and give full play to their strengths, initiative and creativity. However, because students, especially lower grade students, are vague about their goal mode of independently designing and meeting the social requirements, it is also difficult to optimize the learning plan to achieve the goal. Therefore, with the credit system, we should set up guidance tutors to guide students and help students correctly deal with the problems arising in the learning process. Taking Harvard University as an example, which first implemented the credit system, it experienced several stages, such as free elective, limited elective, and \"comprehensive development of the element structure system\". \"Professional field\" required to study the course, study period and the number of courses per semester should be taken are relatively strict regulations.