The invention discloses an insulating ladder safe in use, and relates to the technical field of insulating ladder for electric power. The insulating ladder comprises an insulating ladder body, wherein the insulating ladder body comprises two main supporting rods, a plurality of cross arms, two supporting seats, two magnetorheological fluid dampers and a controller; the plurality of cross arms are connected between the two supporting rods; when the insulating ladder is being used, the controller enters a working mode to detect the angle change between the main supporting rods and the supporting seats in real time through an angle sensor; when the angle change amount reaches or exceeds a threshold value, the controller controls the magnetorheological fluid dampers to electrify and work; the viscosity of a magnetorheological fluid in the magnetorheological fluid dampers is changed, so that piston rods of the magnetorheological fluid dampers are descended slowly by the gravity of a human body, and the descending speed of the ladder is slowed. The insulating ladder can provide active protection during a using process, the accident that users fall off from a high position is prevented; and the insulating adder is high in safety.