The proportion of the post-90s generation of employees in the enterprise is higher and higher, and they are increasingly becoming the main force for the future operation and development of the enterprise. At present, the turnover rate of the younger generation of employees is significantly increased, and their loyalty to the enterprise is obviously lower than that of the older employees. Therefore, the loyalty of the new generation of employees to the enterprise is a matter of great concern to the human resources department of the enterprise. Not only small and medium-sized enterprises, but also large-scale enterprises are also facing the problems caused by the low loyalty of the new generation of employees. In the face of the turnover rate of the new generation of employees, it is very necessary to understand the basic situation of such employees and analyze the factors affecting turnover, especially from the aspects of psychological needs, emotional needs and interpersonal relationships. Only employees can clearly feel that the enterprise can fulfill its commitments and realize its wishes, Achieve balance and improve their loyalty to the enterprise from the perspective of psychological contract. This paper takes the new generation of post-90s employees of Internet data service enterprises as the research object, starting from the relationship between employee psychological contract and employee loyalty, analyzes the impact of psychological contract on the loyalty of the new generation of post-90s employees, and finds the way to improve employee loyalty from the perspective of psychological contract.