A magneto-rheological polishing liquid circulation device that can stabilize the performance of the polishing liquid for a long time. Its liquid mixing tank is connected to the water tank through a metering pump, and the cooler is connected to the liquid mixing tank through a cooling pipeline; The liquid mixing tank, electromagnetic flowmeter, nozzle, recovery device and recovery pump form a polishing liquid circulation loop, and the liquid mixing tank and electromagnetic flowmeter connected in sequence through the non-polishing circulation pipeline form a non-polishing circulation loop, and the polishing liquid circulation loop and the non-polishing The circulation loop is connected in parallel and a switching control valve is provided at the parallel connection of the two. A helical coil is wound outside a section of pipeline between the liquid mixing tank and the switching control valve; the electromagnetic flowmeter and the helical coil are connected to the input end of the computer, and its control The output ends are respectively connected with the switching control valve, the cooling machine, the power pump and the metering pump. The invention has the advantages of high control precision, good stability, etc., and can provide cheap, reliable and stable magnetorheological polishing liquid for magnetorheological polishing processing for a long time.