This paper comprehensively discusses the core application of blockchain technology in information data security protection. First， the basic working principle of blockchain is introduced， including the creation of transaction records， the generation of blocks， the verification process and the update broadcast of the blockchain. Then， the specific application steps of blockchain technology in protecting information data are discussed in detail， such as data initialization， verification， storage and access control， and the method of maintaining system integrity through audit and transparency assurance is expounded. In addition， strategic suggestions were also put forward to strengthen blockchain network security， realize cross chain technology， enhance privacy protection functions， and strengthen the training of relevant personnel to optimize the implementation effect of blockchain technology.