A pulley device, comprising: a pulley housing ; a sliding plate (2-3) which is vertically movable and mounted on the pulley housing ; a pulley (2-2) mounted on the sliding plate (2-3); a height adjusting mechanism for adjusting the height of the pulley; and a damper connecting the sliding plate (2-3) and the pulley housing ; the height adjusting mechanism comprises a first projection (2-1) and a second projection (3-2) that can match with the first projection (2-1), and the first projection (2-1) is disposed on one end of the sliding plate (2-3), and the second projection (3-2) is mounted on the pulley housing and rotatable, and the height of the pulley (2-2) can be adjusted when the first projection (2-1) stands against different positions of the second projection (3-2) ; characterized in that , the height adjusting mechanism further comprises a fixing block (3-1) mounted on the pulley housing , an adjusting assembly drives the rotation of the second projection (3-2), and the adjusting assembly penetrates through the fixing block (3-1) ; the adjusting assembly comprises a front adjusting lever (3-6) and a back adjusting lever (3-7) mounted on the front adjusting lever (3-6), and adjusting holes are provided on both the front adjusting lever (3-6) and the back adjusting lever (3-7) ; the adjusting assembly further comprises an anti-falling step (3-6-1) and a connecting pin (3-6-2), the fixing block (3-1) is provided with a groove (3-8), and the anti-falling step (3-6-1) is fitted in the groove (3-8) of the fixing block (3-1), and the connecting pin (3-6-2) passes through a center hole of the second projection (3-2). a pulley housing ; a sliding plate (2-3) which is vertically movable and mounted on the pulley housing ; a pulley (2-2) mounted on the sliding plate (2-3); a height adjusting mechanism for adjusting the height of the pulley; and a damper connecting the sliding plate (2-3) and the pulley housing ; the height adjusting mechanism comprises a first projection (2-1) and a second projection (3-2) that can match with the first projection (2-1), and the first projection (2-1) is disposed on one end of the sliding plate (2-3), and the second projection (3-2) is mounted on the pulley housing and rotatable, and the height of the pulley (2-2) can be adjusted when the first projection (2-1) stands against different positions of the second projection (3-2) ; characterized in that , the height adjusting mechanism further comprises a fixing block (3-1) mounted on the pulley housing , an adjusting assembly drives the rotation of the second projection (3-2), and the adjusting assembly penetrates through the fixing block (3-1) ; the adjusting assembly comprises a front adjusting lever (3-6) and a back adjusting lever (3-7) mounted on the front adjusting lever (3-6), and adjusting holes are provided on both the front adjusting lever (3-6) and the back adjusting lever (3-7) ; the adjusting assembly further comprises an anti-falling step (3-6-1) and a connecting pin (3-6-2), the fixing block (3-1) is provided with a groove (3-8), and the anti-falling step (3-6-1) is fitted in the groove (3-8) of the fixing block (3-1), and the connecting pin (3-6-2) passes through a center hole of the second projection (3-2). <EOS>