The invention provides a position adjusting device for a centrifugal pump test and an operation method thereof. The position adjusting device comprises a rotating mechanism and a lifting mechanism; the rotating mechanism comprises a supporting assembly, a rotating driving assembly and a rotating round table; a supporting column of the supporting assembly is rotatably connected with the rotating round table, a plurality of idler wheels are hinged to a frame to support the rotating round table, a toothed chain ring of the rotating driving assembly is fixedly connected to the rotating round table, a rotating motor is connected with a transmission gear, and the transmission gear is in engaged connection with the toothed chain ring; the lifting mechanism comprises a lifting frame, a lifting driving assembly and a bearing platform; a frame seat of the lifting frame is fixedly mounted on the rotating round table, driving rods of the cross frame are rotatably connected with transmission rods of the cross frame, the top ends of the driving rods are hinged to the bearing platform, the bottom ends of the driving rods are hinged to the frame seat, the top ends of the transmission rods are hinged to the bearing platform, and the bottom ends of the transmission rods are hinged to a sliding guiding rod; and two slideways are formed in the frame seat in standoff and sunken modes, pulleys at the two ends of the sliding guiding rod are embedded into the slideways, and hydraulic cylinders of the lifting driving assembly are arranged between the sliding guiding rod and the driving rods in a hinged mode.