The present invention discloses a cloud-side collaborative multi-mode private data circulation method based on a smart contract, including: S1, a system is initialized; S2, the original data are encrypted into private data, an encryption certificate z′ for storage is generated, and z′ includes metadata and a data certificate key′; S3, the DO calls a smart contract program to realize uplink of the encryption certificate z′ and releases z′ to a block chain through a smart contract, wherein the smart contract is open to all user accounts; S4, rapid data circulation is realized: when DO releases the data certificate, DU has been identified, a DU's account IDDU is set through an access policy, the DU obtains an encryption key for data access by executing a smart contract and a key algorithm, private data are obtained through metadata and decrypted to obtain a plaintext; and S5, the data circulation is confirmed.