The invention provides a detecting device and a detecting method for an oil pump of an engine, and relates to the field of oil pump detecting. The detecting device comprises an oil storage tank, the oil pump, a driving motor, a torque meter, an air pump and a flowmeter, wherein oil pipes are fixedly connected between an oil outlet of the oil storage tank and an oil inlet of the oil pump, an oil outlet of the oil pump and an oil inlet of the flowmeter, an oil outlet of the flowmeter and an oil inlet of the oil storage tank correspondingly; an overflow valve is connected between an outlet of theoil pump and the oil storage tank; and temperature sensors are fixedly inserted into pipe walls, close the oil inlet and the oil outlet of the oil pump, of the oil pipes, and the oil storage tank correspondingly. The detecting device and the detecting method for the oil pump of the engine solve the problem that only a volume efficiency requirement is stipulated in current industry standard JB/T8413-2010 technical requirements and test methods, and the gas content of engine oil cannot be measured by a relatively systematic scheme for testing the oil pump volume efficiency, the gas content of the engine oil and total efficiency.