The invention discloses a system and a method for sharing confidential data on a blockchain. The system comprises a data encryption subsystem, a key distribution subsystem, a metadata directory subsystem, a key collection subsystem, a data decryption subsystem and a confidential data storage subsystem. The invention belongs to the technical field of blockchains. The invention relates to a system and a method for sharing confidential data on a blockchain. After the key is segmented, the key is stored on blockchain and is prevented from being lost, an innovative data use and supervision mechanism is provided; after the data provider encrypts the data, the key fragments are distributed to each holder, and each key fragment holder is a data stakeholder or a data supervision mechanism; when a user wants to win the encrypted data, the user needs to obtain approval of each holder; and, through the mechanism, it can be clearly recorded that the data is provided, supervised and used by who, andall historical records cannot be changed, and reasonable and legal exchange and use of the data in the digital economy era, business and personal data can be effectively guaranteed.