With the advent of the information age, the effective identification of sensitive information and the leakage of sensitive information during the transmission process are becoming increasingly serious issues. We designed a sensitive information recognition and encryption transmission system based on a decision tree. By training sensitive data to build a decision tree, unknown data can be classified and identified. The identified sensitive information can be marked and encrypted to achieve intelligent recognition and protection of sensitive information. This lays the foundation for the development of an information recognition and encryption transmission system.