In order to solve the weakness of manual operations, data accuracy and security in bulk goods weighing. In this paper, based on contactless IC Card in truck scale weighing system is designed, and the specific workflow is given. Storage structure and access control of Contactless IC Card is analyzed, and RSA encryption/decryption algorithm based on binary tree is proposed. Finally, the sequence diagram of function calling is showed and the operation process of IC card and the reader is described through Specific code. Applying this system to bulk goods weighing, it greatly reduced the time, improved the work efficiency, and ensured the data accuracy and security.