The system of fuel oil flow test is one of the significant ground simulation experiments. The tubes layout in the test reservoir are consistent with that in the real aircraft reservoir, so they are not suitable to be installed in the narrow space of the reservoir. And it will damage the flow resistance characteristic of the tube to install the turbine flowmeter. As the way of traditional reservoir oil calibration wastes work and time, it is necessary to apply a novel technology to fulfill the oil calibration. Because the volume of ultrasonic flowmeter is smaller so it will not ruin the flow resistance characteristic of oil transportation tube which can meet the experiment demand. This paper deals with the possibility analysis of the ultrasonic flowmeter under the circumstances of immersion oil, the creation of ultrasonic flowmeter will be fulfilled in the fuel oil system experiments. The importance of ultrasonic flowmeter in the test of airplane fuel oil will be verified by the experiments. It is significant to make a fuel oil flow test utilizing the ultrasonic flowmeter in the fuel oil system series experiments for the first time. As a result, it is proved that ultrasonic flowmeter plays an important role in the aircraft fuel oil flow test and troubleshooting.