The invention discloses a pulley high-low position adjustment method based on sliding door application. A horizontal gear and a taper tooth screw are in close fit with each other; when the height of a gap between a door panel and a cabinet body needs to be adjusted, the horizontal gear is driven to rotate by a hexagon spanner and drives the taper tooth screw to rotate, and the taper tooth screw rotates left and right to drive a threaded slide block to lift up and down, so that a bearing slide block is pushed to lift up and down to realize up-and-down lifting of an adjusting wheel, and accordingly, the gap between the cabinet body and the door panel can be adjusted. The traditional vertical adjustment method is changed in the way that the horizontal gear is adjusted to realize height adjustment of the sliding door, and the adjustment is quick and convenient. The invention also discloses a sliding door adjusting device which has a simple structure, successfully converts vertical adjustment into horizontal adjustment, is low in manufacturing cost and convenient in use, can effectively prevent an adjusting wheel from jumping on a rail, and is safer in use.