Mobile edge computing(MEC) deploys edge servers to the side of wireless LAN and offloads some computing-intensive tasks to edge cloud servers, which can shorten the distance between computing services and mobile devices and reduce the cost of data transmission.This paper considers the problem of computing task offloading in the mobile edge computing environment. By exploring the heterogeneity of user experience sensitivity, a ternary combination model of the number of CPU cycles, data size and price is established, and a computing task allocation strategy based on contract theory is established to maximize the profit of cloud service providers and ensure the non-negative benefit of mobile users. The optimal contract design strategies for complete information scenarios and statistical information scenarios are discussed, respectively. Simulation results show that the proposed schemes can effectively realize the offloading of computing tasks.