Abstract: Effect of rolling on characteristics of single-phase flow in narrow rectangular channel is in-vestigated experimentally under ambient temperature and atmospheric pressure.The results show that the frictional coefficient and Reynolds number fluctuate periodically when driven pressure head is low,and the more acute the rolling movement,the larger the fluctuant amplitude.When the driven pressure head is high,periodical fluctuate of Reynolds numbers is not obvious,and the amplitude of the friction coefficient fluctua-tion becomes smaller.For the case that test sections with outlet open to atmosphere,the rolling amplitude not only influences the fluctuant amplitude of the friction coefficient but also changes its waveform.The rolling period only has effect on the amplitude.The effect of rolling on the friction characteristics decreases as the mean Reynolds number increases.There is no obvious effect of rolling motions on the mean frictional char-acteristics of the single-phase water flow in narrow rectangular channel.