The volumetric efficiency of rolling piston compressor was studied on a variable refrigerant flow system under the condition of suction vapor quality greater than 0.9.The experimental results show that when 0.9<x<1, volumetric efficiency decreases with the increase of pressure ratio and the decrease of vapor quality.Under the same frequency, volumetric efficiency under different compression ratio shows a similar change trend.The volumetric efficiency of rolling piston compressors with high backpressure and low suction pressure drop decreases slightly under a little liquid entrainment.The decreasing ratio is only 1% under a relatively large quality(x>0.95)and at the rated operating speed.Therefore these compressors are suitable to operate with a little liquid entrainment.