Abstract: An adjustable pulley assembly includes a fixing plate securely mounted on top of an upper frame of a suspended door, an adjusting seat mounted to the fixing plate, a pulley seat securely attached to the adjusting seat to move therewith, a pulley attached to the pulley seat, and an adjusting bolt. An axle is extended through the pulley, a screw hole in the pulley seat, and a vertical slot in the adjusting seat, and a nut is engaged on a distal end of the axle. An adjusting bolt is extended through a hole in a top plate of the pulley seat and a screw hole in a top plate of the adjusting seat. A distance between the top plate of the pulley seat and the top plate of the adjusting seat is changed when the adjusting bolt is turned.