Abstract: The invention relates to adjustable stop-wagon retarders with locking function for wagons at high speed and disposal methods thereof, which are suitable for railway marshaling yards or rail lines where it is required to prevent wagons from running away, which are hydraulic equipment of no external energy source to automatically regulate wagon's speed and disposal methods of such equipment. The stop-wagon retarder is characterized in that a uni-directional return unit comprising a sealing valve plate and adjustable throttle valve, and a locking control valve composing of switch valve and positioning unit are mounted in the piston assembly, which make the returning speed and the locking speed for wagon at high speed adjustable, thus the aim of setting the retarder with different control levels and thresholds according to the wagon speed is realized.