The invention relates to a flowmeter, and particularly to a no-pressure oil flowmeter which realizes flow detection on no-pressure oil through a liquid level sensor, a signal converter and an oil tank which is provided with an oil discharging outlet. The no-pressure oil flowmeter comprises the oil tank. An oil inlet, a ventilating hole and a liquid level meter are arranged above the oil tank. One end of the liquid level meter is inserted into the oil tank, and the other end extends to a position above the oil tank and is connected with a signal converter. The lower end of the oil tank is provided with the oil discharging outlet. The no-pressure oil flowmeter provided by the invention is mounted in an oil return pipeline and can realize a purpose of no-pressure detection for a lubricating flow, thereby preventing lubricating flow detection failure caused by pipeline damage and ensuring reliable lubrication for equipment.