Abstract: Aiming at the problems of data insecurity and data inconsistency existing in traditional information systems, a data protection technology for information systems based on blockchain is proposed. The multi-chain structure is used to divide the permissions of each layer of nodes on hierarchical information systems, so that only the nodes with corresponding rights can access and operate the data. Privacy data veri¯cation technology, anti-forgery technology and non-reputation technology are studied. By using data protection technology, data security of information systems is improved.