The invention relates to a pilot valve and steering device oil taking loop, a loading machine hydraulic system and a method. The pilot valve and steering device oil taking loop comprises a drainage pipeline, one end of the drainage pipeline is connected with a main oil inlet in a flow amplification valve so as to drain pressure oil. The other end of the drainage pipeline is connected with an inletof an oil source valve, and the oil source valve can achieve pressure reducing of the pressure oil flowing in the oil source valve. An outlet of the oil source valve is connected with a first branchpipe and a second branch pipe, wherein the first branch pipe is used for being connected with a main oil inlet of a steering device, and the second branch pipe is used for being connected with a mainoil inlet of a pilot valve. The oil source valve comprises a pressure reducing valve and a one-way valve which communicate with each other in sequence, the drainage pipeline is connected with an oil inlet of the pressure reducing valve, and an oil outlet of the one-way valve is connected with the first branch pipe and the second branch pipe. By means of the pilot valve and steering device oil taking loop, the loading machine hydraulic system and the method, the defects generated by supply oil through a pilot pump for an existing pilot valve and an existing steering device can be overcome, useof the pilot pump is omitted, and therefore the cost and space are saved.