Abstract: The acceleration of globalization and the rapid development of electronic transactions have led to a booming growth in the demand for multimodal transport, an efficient logistics mode. The multimodal transport process involves a large amount of data exchange and real-time communication, and the potential security risks of data have become increasingly prominent. Against this background, an innovative data security encryption scheme that combines domestic encryption technologies with blockchain has been constructed. By analyzing the business processes and requirements of multimodal transport and integrating specific business areas, the architecture of the blockchain platform has been designed. Domestic encryption algorithms technology such as SM2, SM3, and SM4 are used to achieve encrypted transmission and storage of data, ensuring the security and integrity of data. The experimental results show that this scheme performs excellently in terms of data anti-leakage, real-time performance, and stability, meeting the practical application requirements in the field of multimodal transport.