The utility model discloses an automatic engine oil filling device for a passenger car, which comprises an engine, an oil pan, a liquid level sensor, an engine oil box with a pump and a control indicator light, wherein the liquid level sensor is mounted at the joint of the housing of the engine and the oil pan; the sensing head of the liquid level sensor passes through the side wall of the housing of the engine and extends into the inner chamber of the housing of the engine; the liquid level sensor is electrically connected with the engine oil box with the pump through a conducting wire with which the control indicator light is connected in series; and the oil pipe of the engine oil box with the pump is connected with the engine oil filling port of the engine. The automatic engine oil filling device can reasonably control the engine oil consumption to realize ideal oil control, prolongs the maintenance period, avoids engine early-stage wear caused by insufficient lubrication, or energy wastage caused by excessive engine oil, and meanwhile, effectively reduces the engine oil consumption during maintenance.