The invention relates to the technical field of data transaction, in particular to a data transaction method based on a block chain, which comprises the following steps: acquiring original
consumer transaction data, then executing multi-layer
encryption, binding hash value storage after secondary
encryption by a block chain node, calling an intelligent contract to match a public key address and authority, and storing the public key address and authority. And monitoring the
active state and transaction volume of the block
chain network in real time, calculating a log structure by adopting a chained hash process, writing the log structure into a non-tampering storage layer, and generating an audit log identifier. According to the method, the flexibility and efficiency of
data access are optimized through intelligent contract automatic
verification and dynamic allocation of access permissions, meanwhile, safe
data access management is enhanced according to matching of public key addresses and permission conditions and dynamic calculation of
consumer credit scores, and the real-time transaction volume and the node
active state of a block
chain network are monitored; the stability and the response speed of the network are improved, and the security, the efficiency and the reliability of the data in the transaction process are enhanced.