In the express service industry, the status of express service providers and consumers is virtually unequal. It’s not only that consumers can’t be compared with the express enterprise in personal strength, but also in the unfavorable situation of information asymmetry throughout the express service process, express mail once it enters the delivery link will be divorced from the actual control of consumers, which can only rely on express enterprise information feedback. Therefore, in the express service relationship, the consumer is actually in a serious weak position. On the one hand, consumers do not enjoy the full “discourse right” in the process of express service; on the other hand, it can not guarantee the quality of the service provided by the express enterprise. In practice, express delay, loss, damage and other phenomena occur frequently, the legitimate rights and interests of consumers are often subjected to various violations. Obviously, the status of the two sides are not equal to the express service market, the market only rely on the role of spontaneous regulation has been unable to meet the real needs, so it is extremely necessary to use legal intervention to maintain the order of the express market and balance the gap between the two sides. In order to achieve this goal, China has gradually established a system of express service quality assurance legal mechanism through years of legal construction. Research on the legal mechanism of express service quality guarantee in China must face the weak position of consumers, from the perspective of the protection of consumer rights on the existing legal mechanism for inspection, analyze the problems for the legal system of express service in advance, in the matter and after the event, put forward the effective countermeasures to improve the legal system of express service quality assurance under the guidance of the theory “consumer sovereignty”, found that through legal means to protect the essence of express delivery service quality, to promote the express service market benign operation.