The invention discloses a sharing transaction metadata method, device and system based on block chains; transaction metadata can be extracted from various party transaction data and written into the block chain, thus forming a distributed shearing transaction metadata block chain account book; the method comprises the following steps: issuing a digital signature certificate based on a PKI / CA system for block chain nodes and transaction various parties, recording transaction metadata, and signaturing the block in a secrete manner; desensitizing transaction main body information, extracting transaction metadata from original transaction data, uploading the transaction metadata to block chain nodes, allowing the transaction main body to confirm the transaction metadata, allowing the block chain node to write the confirmed transaction metadata into the block chain, and allowing data sharing parties to check the block chain information after authorization. In an authority issuing business scene, the original transaction and collateral data are encrypted and stored through a storage service module, and related transaction authorities are provided for the transaction sharing party, the transaction main body and the transaction main body opponent party.