Single rope grab bucket opening and closing is mainly elastic elements car-riage and lock with exercise etc. During grabbing material, the open grab will fall upon materials, the steelcable drios to make sliding mechanism slide down, due to the effect of springs mechanism, the grab fouches the hook, then the driver lifts the sliding mechanism to lift lower separator and close jaw. During unloading materials, the filled grab is transferred to material accumulation or above ground, the steel cable drops to make the sliding mechanism fall for a distance and pressure on the grab from hook will disappear, due to the effect of spring on head, the grab will tum to go off hook, the driver re-lifts and the jaw will open due to effects of lower separator and material dead load.