The invention discloses a constant-value synchronous operation method and device for distributed element protection. The constant-value synchronous operation method adopts a method for remotely synchronously modifying the protective constant value of each sub-machine and a method for remotely synchronously switching the constant value area of each sub-machine. The constant-value synchronous operation device includes a portion for remotely synchronously modifying the protective constant value of each sub-machine and a portion for remotely synchronously switching the constant value area of eachsub-machine, wherein the portion for remotely synchronously modifying the protective constant value of each sub-machine comprises synchronously constant value area switching units, a management mainframe commands of constant value area switching to the sub-machines, the sub-machines switch constant value areas and then feeds area switching results and constant value CRC back to the management mainframe, and the management mainframe summarizes the information of all the sub-machines and replies to client-sides. The method is feasible for protective constant-value correction of distributed installed and cross-interval elements with main configurations, ensures the consistency of the protective constant values of all sub-machine in operation, and provides guarantee for the reliable and stableoperation of a relay protection device.