In order to investigate the wet gas performance of ultrasonic flow meter，the wet gas flow characteristics were taken into account and the experiment was carried out with a two-path V turn reflection ultrasonic flow meter.The test result showed that the wet gas over-reading of ultrasonic flow meter was dependent on the L-M parameter.Liquid hold up and depth of liquid at the pipe bottom were the leading factors that affected the over-reading of ultrasonic flow meter with reflection sonar path.Consideration was given to liquid hold up，and a theoretical wet gas correlation of ultrasonic flow meter was deduced，the gas flow rates could be predicted within ±3% error under the flow condition when the L-M parameter was less than 0.1.This research work is useful for developing wet gas flow meter based on ultrasonic technology.