The invention discloses a blockchain data transaction system and a blockchain data transaction method based on proxy re-encryption and an intelligent contract. The system comprises a data owner terminal, a database system, a blockchain system, a data demander terminal and an intelligent contract module. According to the method, the security privacy of the transaction data can be ensured by using the proxy re-encryption technology, and the efficient and automatic execution of the data transaction can be realized by using the smart contract, so that the security privacy and efficiency problems of the blockchain data transaction are solved. The economic value of the data is realized, and the application value of the data is brought into full play.