The invention belongs to the field of designs of return pipelines of rectifying towers and particularly relates to an improved water-cooling heat-exchanging circulating system and a control method thereof, wherein the system comprises a water-cooling heat exchanger inlet pipeline, a water-cooling heat exchanger, a water-cooling heat exchanger outlet pipeline and a material receiving storage tank. A first valve is arranged on the water-cooling heat exchanger inlet pipeline, a second valve is arranged on the water-cooling heat exchanger outlet pipeline, a cross-over pipe is arranged in a position of the water-cooling heat exchanger, the cross-over pipe strides over the first valve, the water-cooling heat exchanger and the second valve, a third valve and a fourth valve are arranged on the cross-over pipe, an external connecting pipe is connected between the third valve and the fourth valve, and the external connecting pipe is connected to other material pipelines. The improved adjusting operation not only increases the temperature of a material outlet of the water-cooling heat exchanger, but also increases the flow rate of circulating water and guarantees that the water-cooling heat exchanger is not damaged. Moreover, when the heat exchanger is damaged and needs to be overhauled, the heat exchanger can be safely taken out to be overhauled on the premise of guaranteeing no shut-down, thereby killing three birds with one stone.