The utility model relates to the technical field of a breaker actuating mechanism, in particular to a breaker actuating mechanism brake-separating releasing force testing device. A mechanism releasing half-shaft and a mechanism rotating shaft are arranged on a support of the breaker actuating mechanism, the breaker actuating mechanism brake-separating releasing force testing device comprises a base, a pneumatic loading assembly arranged on the base, a constant value force device assembly oppositely arranged on the pneumatic loading assembly, a crank connecting link assembly, a force testing mechanism and a solenoid valve connected with the pneumatic loading assembly. One end of the crank connecting link assembly is connected with the constant value force device assembly, and the other end of the crank connecting link assembly is connected with the mechanism rotating shaft. The breaker actuating mechanism brake-separating releasing force testing device is simple in structure, convenient to operate, capable of stably detecting constant value force, and wide in application scope, and improves work efficiency.