The invention discloses an adjusting device for a hydraulic forklift. The adjusting device mainly solves the problems of the poor drive capacity and small lifting capacity existing in the prior art. The adjusting device comprises an oil tank filled with hydraulic oil, a gear pump provided with an inlet formed in the oil tank and used for pressing the hydraulic oil, a check valve arranged on an outlet of the gear pump, a three-position four-way reversing valve with an inlet connected with the check valve and an outlet connected with the oil tank and an oil cylinder connected with the reversing valve. A filtering screen for filtering returned oil is vertically arranged in the oil tank. A ventilation hole for oil injection and exhaust is formed in the top of the oil tank. By means of the scheme, the adjusting device has the beneficial effects of being high in drive capacity, agile to operate, stable in hoisting and the like and has the extremely high practical value and promotional value in the field of hoisting equipment.