According to the rapid feed hydraulic system design requirements of truck-mounted rig，related parameters of advancing hydraulic cylinder were analyzed and determined.According to the characteristics of rapid feed,control pressure and capacity of multi-way steering valve under different working condition were analyzed,to verify the rationality of the design selection.The design solution of rapid feed hydraulic system was proposed and its working characteristics were analyzed.It provides theoretical references for subsequent design and research of this type of rig.This method has some reference value for the same type drilling rig design.