The invention relates to a moment measuring device for a circuit breaker body. The moment measuring device comprises a force transducer and a driving mechanism of which one end is used for being connected with an outer crank arm of a circuit breaker, wherein the other end of the driving mechanism is fixedly connected with the input end of the force transducer. The moment during the process of two limit positions of brake separating and closing of the qualified circuit breaker verified by tests is selected as a research object and relevant mechanical principles are combined to measure the moment of a main crank arm of the circuit breaker in the motion process and a standard characteristic curve is drawn for guiding subsequently-operated debugging work of a 800kV circuit breaker body and judging whether the assembly characteristics of the circuit breaker meet the work requirements or not, and thus the debugging time is shortened, the assembly and detection level of the circuit breaker are improved and the characteristics of the circuit breaker are improved.