The invention discloses a prepressing adjustable sliding valve throttling device, and relates to the technical field of static pressure. The prepressing adjustable sliding valve throttling device comprises an outer sleeve, a sliding valve and an adjusting assembly, the outer sleeve, the sliding valve and the adjusting assembly form a pre-pressing cavity, a throttling gap A for communicating with an oil inlet and a pre-pressing cavity is formed between the outer sleeve and the sliding valve, and a throttling gap B for communicating with an oil outlet B and the pre-pressing cavity is formed between the adjusting assembly and the outer sleeve. The device has the beneficial effects that pressure oil pre-pressing is adopted in the sliding valve, vibration of the sliding valve during work can berestrained, the sliding valve can stably move, and the sliding valve throttling stability is improved; the adjusting assembly is rotated, the initial value of the conical throttling gaps can be adjusted, the adjusting of the throttling ratio can be achieved, the device can adapt to different machining and assembling errors of a static pressure device, and working condition changing needs, in thework process, according to the loads, the adjusting assembly can be subjected to micro adjusting, the ideal throttling ratio can be obtained, and the throttling device works in the optimal work stateadapting to the loads.