As the digital economy develops, the use of digital methods for the storage of financial documents is being commonly adopted. To protect the data security of financial documents and ensure the traceability of data, this article designed a secure storage and traceability system for financial documents based on blockchain. Firstly, a blockchain platform with a private chain that had better security and scalability was selected, and the data structure and smart contract design were then carried out. Secondly, an identity authentication and permission management mechanism was established, and data storage and transaction processing modules were designed. Asymmetric encryption was used to secure data, and the digital signatures were combined to ensure the integrity of financial documents. Finally, the traceability function was achieved through the immutability of blockchain technology. The task of storage and traceability was accomplished by designing a secure storage and traceability system for financial documents in conjunction with the blockchain technology. In the experiment, it only took about 50 seconds to process traceability tasks with an interval of 50 people, which was shorter than the traditional system’s 180 seconds; it also maintained an accuracy rate of over 90% in traceability tasks with an interval of 100 people; in the face of 1000 network attacks in a short period of time, the financial management system based on blockchain technology was only invaded 20 times, while the traditional financial system was invaded 200 times. This system, in terms of time, traceability accuracy, and data security, were all improved over the traditional system. The design of a secure storage and traceability system for financial documents based on blockchain technology is conducive to strengthening the security of data and the accuracy of traceability.