The invention discloses a method for updating a paxos instance. The method includes: after a proposal node receives a plan update request, it directly executes the preparation process for updating the paxos instance, determines the sequence number, and obtains a request from each approval node during the preparation process. Obtain the status information of the current plan, the status information of the current plan includes: the instance ID, value and serial number of the approved paxos instance under the current plan; the proposal node obtains the instance ID of the paxos instance that needs to be updated according to the state information of the current plan , and execute the approval process of the paxos instance to be updated with the instance ID and the serial number determined by the preparation process. Correspondingly, the present invention also discloses a device and system for paxos instance update, which integrates the learning process in the paxos algorithm into the preparation process, simplifies the execution process of the paxos algorithm, improves the execution efficiency of the paxos algorithm, and solves the problem of It solves the problem of low execution efficiency of the existing paxos algorithm.