A circulation pump for circulating downhole fluids is provided. The circulation pump includes a cylindrical pump housing, a shaft secured in the pump housing extending in a longitudinal direction thereof, an impeller rotating around the shaft in the pump housing, a cylindrical magnetic coupler rotating around the pump housing, the cylindrical magnetic coupler including a magnet, and a motor positioned outside of the pump housing and connected to the magnetic coupler to rotate the magnetic coupler around the pump housing. The impeller is provided with a magnetic piece, which is capable of being magnetically connected with the magnet of the cylindrical magnetic coupler to cause the impeller to rotate around the shaft by rotating the cylindrical magnetic coupler around the pump housing.