A data security protection model based on OTFE is designed for security problems such as data leakage in power business terminal. This paper uses file system filter driver technology and CRT-AES encryption & decryption algorithm to achieve the transparent encryption and decryption of terminal sensitive data. Controlling the user’s permissions to access and transmit terminal sensitive data according to the terminal data policy, and recording data operation process by operation log. Proved by examples, this model can encrypt the storage and control transmission of the terminal data, and provide the effectively theoretical basis for the security of the terminal data.