College students' off-campus internship is an important way to improve professional skills and employability. It is an internal requirement to cultivate students' social responsibility, innovative spirit and practical ability, and improve their quality. There are some problems in college students' off-campus internships, such as the government's support for university students' internships support policies is insufficient, colleges and internship units do not have effective management mechanisms, the internship unit lacks incentives and security policies for internships, some intern students lack proper attitudes toward internships, and the lack of effective legal protection for university students during the internship period, which affect the effective development of internship activities and the quality of internships. Through the analysis of the problems existing in college students' off-campus internships, some guarantee measures to improve the quality of college students' off-campus internships, such as strengthening the support of government policies and legal systems, strengthening the university internship organization, strengthening the internship process management, strict evaluation of internship results, and improvement of practice safety precautions, etc. are put forward. Strengthening the quality of college students' off-campus internships is of great significance to safeguarding the legitimate rights and interests of college students and improving the quality of personnel training.