The power communication network based on 5G network slicing is an important foundation to support smart grid, and the bearing of small granularity power regulation and control class services depends on the slicing soft isolation technology, and the data isolation between each soft isolation channel is crucial. In this paper, we propose a new symmetric cryptographic algorithm based on random coding, and establish a hybrid encryption method based on this symmetric algorithm, combined with SM2 and SM3 algorithms, which is suitable for encrypting the data of power regulation and control services. It is also verified through simulation that the proposed hybrid encryption method has high encryption efficiency while ensuring security.