Method for automatically supplementing oil content of engine and refueling system

The engine comprises an oil pan, an oil storage tank, a first oil way, a second oil way, a first sensor and an engine oil content detector, the oil storage tank and the oil pan are arranged at intervals from top to bottom, the oil storage tank is provided with an oil inlet, the first sensor is arranged in the oil storage tank, and the second sensor is arranged in the second oil way. The first oil way and the second oil way are communicated with the oil storage tank and the oil pan respectively, and a first valve is arranged on the second oil way; the engine oil content detector is arranged in the oil pan and used for detecting the engine oil content in the oil pan; the engine oil content automatic supplementing method comprises the steps that the height value of the liquid level in the oil storage tank is obtained; when the height value is smaller than a first threshold value, a first engine oil content value in the oil pan is obtained; and when the first engine oil content value is smaller than the second th