The invention provides an inertial separation device capable of efficiently utilizing energy. The inertial separation device comprises a cylinder and a fluid director arranged in the cylinder. The cylinder is provided with a liquid collection cavity, a mixed medium inlet, a liquid outlet end, and a gas output channel, wherein the mixed medium inlet, the liquid outlet end, and the gas output channel are communicated with the liquid collection cavity. The mixed medium inlet is used to introduce a gas-liquid mixed medium into the fluid director to carry out separation. The gas output channel is used to discharge separated gas. The liquid outlet end is used to discharge separated liquid and fine solid particles. The inertial separation device comprises a motor assembly, which comprises a rotation shaft and a motor. One end of the rotation shaft is connected to the motor in a drive mode, and the other end is arranged in the cylinder in a through mode. The fluid director is connected to therotation shaft and is configured to drive the rotation shaft to rotate by utilizing the energy of the gas-liquid mixed medium that is introduced into the device from the mixed medium inlet, and the motor is driven by the rotation shaft.