The gas anchor is installed at the suction port of the pump, and its function is to separate some of the gas before the downhole fluid enters the pump, reducing the impact of gas on the pump and improving pump efficiency. The gas anchor is a three-stage separation gas anchor, with the first stage being a settling separation device consisting of multiple settling separation bowls, and the second and third stages being spiral separation devices consisting of a central tube and spiral blades, with a dual channel separation valve on the upper part. When the gas-liquid mixture enters the first stage, the gas and liquid undergo preliminary separation by gravity. The liquid enters the gas anchor through the central tube, and the gas is discharged from the small hole at the top of the separation bowl. In the second and third stages, gas and liquid are separated again by centrifugal force. The gas is discharged through the internal gas collection pipe and gas-liquid separation valve, while the liquid passes through the external annular passage and gas-liquid separation valve to reach the suction port of the pump. This multi-stage gas anchor can effectively separate gases from crude oil.