The invention discloses a measurement method of GIS fully enclosed 126KV combined circuit breaker contact persistence. The method comprises the following steps: in the first outlet circuit of a circuit breaker, separately turning off a first isolating switch, a second isolating switch and a second earthing switch, switching on a first earthing switch, a third isolating switch and a circuit earth side switch, simultaneously dismantling the logic blocking device between the earthing switches and isolating switches and the earthing connecting bar of R, S and T of the circuit earth side switch, and connecting the connection end of R, S and T of the circuit earth side switch with a loop resistance tester used for measuring the contact resistance of each phase of the circuit breaker. The methodof the invention can be used to effectively, fast and accurately measure the contact resistance of the circuit breaker without disintegrating the circuit breaker; the measurement method uses movable and fixed contacts of each phase of the circuit breaker to form contact resistance for measuring each contacts in the measurement loop so as to avoid the original defect of separately measuring movableand fixed contacts of each phase of the circuit breaker.