The invention belongs to the technical field of heat pumps, and discloses a multi-machine parallel heat pump system. The system comprises a circulating pipeline, a plurality of main machines, a controller, a circulating pump and a flow control assembly, wherein the circulating pipeline comprises a liquid inlet pipeline and a liquid outlet pipeline, a liquid inlet of each main machine communicateswith the liquid inlet pipeline through a liquid inlet branch pipe, a liquid outlet of each main machine communicates with the liquid outlet pipeline through a liquid outlet branch pipe, a control valve is arranged on each liquid inlet branch pipe, when one or more main machines is stopped, the controller controls the control valves to cut off the liquid inlet branch pipes of the main machines, thecirculating pump is arranged on the circulating pipeline, and the flow control assembly is connected with the controller and the circulating pump, and is used for controlling flow of a fluid in the circulating pipeline can be controlled according to the temperature difference value delta T of a fluid in the liquid outlet pipeline and a liquid in the liquid inlet pipeline. According to the system,the fluids can be prevented from flowing through the non-working main machine, and the flow can be adjusted according to the temperature change of the fluid in the circulating pipeline.