The invention relates to the technical field of aluminum alloy material machining equipment, and discloses a safety protection device for the aluminum alloy plate cutting machining. The safety protection device comprises a workbench, a rotating shaft is movably connected into the workbench, a first chain wheel fixedly sleeves the rotating shaft, a chain is engaged with the exterior of the first chain wheel, and a connecting rod is movably connected with the exterior of the chain; a sliding rod is movably connected to the outside of the connecting rod, and a sleeve rod is movably connected to the outside of the sliding rod; through interaction among a connection rod, a shell, a limiting block, an electro-rheological body, an electric wire, a movable block, a speed reducing block, a first spring, a second spring and a monitoring assembly, the rotating speed of a lead screw can be limited in time when the rotating speed of the lead screw exceeds a normal speed range due to stall of a motor in the aluminum alloy plate cutting machining process; and the rotating speed of the lead screw is gradually reduced, so that the situation that the cutting blade is broken due to the fact that themoving speed of the lead screw is too high is avoided, and meanwhile continuous cutting of an aluminum alloy plate is not affected.