The invention provides a transaction method and system based on the block chain Internet of things. The method comprises steps that a transaction agreement for service products is established by a transferor through a block chain account, after the transaction agreement is signed, the transaction agreement is deployed on a block chain; after the corresponding transaction agreement is queried by atransferee through a block chain account and is signed by the transferee, transaction tasks as stipulated in the transaction agreement are initiated; a transaction intermediate request for executing the transaction agreement is received by a data processing node of the block chain, and the transaction tasks stipulated in the transaction agreement are accomplished according to the transaction intermediate request. The method is advantaged in that transaction fairness and legitimate rights and interests of both parties in the sustainable transaction of the Internet of Things under the group intelligence environment can be guaranteed not to be infringed, historical transaction record that can be followed and can not be tampered with can be further provided, and group intelligence service transaction supervision is facilitated.