The effect of single oil supply volume on the oil content and oil fluctuation under oil-air lubrication was investigated with electrical capacitance tomography technology on the designed test bed at a certain air pressure.The results show that，with the increase of single oil supply volume，the average velocity of oil fluctuation presents the changing law of inverted U-shaped,the amplitude of oil film wave becomes smoothly,and the oil content in pipe is increased rapidly at the beginning and then increased slowly.