The design document is an important basis for the establishment, construction and production of power engineering construction. After the power engineering design documents are completed by the design unit, they are usually distributed to other units in the form of printing paper documents and making blueprints. The current method of document distribution has resulted in higher costs of document printing and storage, and the efficiency of document distribution is low. In this paper, a searchable power engineering design file distribution model based on the Alliance chain is stated. It uses the main feature of the blockchain's data tamper-proof technology, and combines the searchable encryption technology to realize the distribution and access management of digital power design files, eliminating the problems of inconsistent file versions and malicious tampering of file contents in the existing design file distribution process. In this model, the feature information ciphertext and keyword index ciphertext of the design file are written into the block data of private chain of design unit, and private chain send transaction to alliance blockchain. At the same time, the design documents are stored in distributed file systems, and the feature information of the documents is compared during the access of the design documents, so that the design documents can be tamper-proof after distribution, and the solution of replacing the paper blueprints with digital design drawings is realized. The model can make the engineering documents have the ability of tamper-proof, and can trace the flow process of the documents.