Abstract: Experimental studies of singlephase pressure drop in narrow rectangular channel under rolling motion were carried out. The rolling periods were 8, 12, 16 s, and the rolling angles were 10°, 15°, 30°. Experimental results show that the frictional factors periodically fluctuate with time. The amplitude and average value of frictional factors decrease with the increasing of Reynolds numbers. At any moment, the transient frictional factors increase with the increasing of rolling angular acceleration.