The invention relates to a simple oil separator for an automobile air conditioner system. The simple oil separator comprises an oil separation bent pipe and an oil storage cavity. The oil separation bent pipe penetrates through and is fixed to the upper portion of the oil storage cavity in the mode that the two ends are exposed, the two ends of the oil separation bent pipe are a refrigerant inletend and a refrigerant outlet end, the arc face on the side with the large curvature radius of the oil separation bent pipe or a straight pipe section connected with the tail end of the arc face on theside is provided with an oil separation port, and the oil separation port is located in the oil storage cavity. The lower end of the oil storage cavity is provided with an oil return mechanism. In the oil output direction, the oil return mechanism is formed by sequentially connecting a throttling hole, an oil drainage hole and an oil return port. The oil drainage hole is a variable-section hole with the cross section increased gradually. According to the simple oil separator, in the flowing process of gas state refrigerant and liquid state refrigerating machine oil in the oil separation bentpipe, oil separation is achieved under the effect of weight and inertia. Oil enters the oil storage cavity through an oil separation port and returns back into a compressor of the air conditioner system through the oil return structure. The simple oil separator has the advantages of being small in size, simple in structure and resistant to vibration.