With the continuous improvement of the status of private universities in national education, the demand for talent cultivation is also increasing. How to enhance employee loyalty is the key factor to the sustainable development of private universities. As a supplement to economic contract, psychological contract plays an important role in maintaining employee morale and enhancing employee loyalty. Based on the perspective of psychological contract, this paper conducts research on improving employee loyalty of private colleges and universities. Firstly, the article sorts out the relevant domestic and foreign literature, and introduces related theories and concepts on this basis; secondly, the article uses the questionnaire survey method to investigate and analyze the current situation and existing problems of employee loyalty; thirdly, with the help of reliability, validity and the factor analysis method, the article analyzes the employee's psychological contract and loyalty, and gets the inevitable connection between psychological contract and employee loyalty. Research shows that transactional psychological contracts, relational psychological contract and growth psychological contract have significant positive impacts on loyalty. Based on the results of the empirical analysis, it is suggested that private colleges and universities propose strategies to enhance employee loyalty in terms of creating a good working environment, encouraging participation in school management, scientific career planning, appropriate spiritual rewards, and respecting and trusting employees.