The invention discloses a blockchain-based copyright trading system and a trading method. The blockchain-based copyright trading method comprises creating the copyright trading system, and the trading system comprises a system platform, a shopping mall platform and bottom blockchains. The method is characterized in that a user is registered as a platform user through the system platform, and the system platform issues a unique public-private key pair and a unique user ID for the platform user; a copyright owner uploads a work to the shopping tall platform, and adds signatures of public and private keys to the work; the shopping mall platform verifies signature information of the copyright owner through the private key, and generates fingerprint information uniquely corresponding to the signature information for the work; and the system platform creates a blockchain transaction, and perform cochain on fingerprint information, copyright owner public key encrypted data, the copyright owner ID, a transaction type, a credible timestamp and the platform private key signature, which are taken as transaction data, at the same time. All transaction details are recorded by utilizing the blockchains, and then copyright trading is very secure.