Abstract: Resistance characteristics of pulsating laminar flow in a rectangular channel were investigated analytically and experimentally. Mathematical model of laminar flow was established. The influences of the flow fluctuation period and relative amplitude on friction constant were analyzed. Analytical results were verified by experiment. The results show that friction constant in pulsating laminar flow is a function of pulsating period, relative amplitude, aspect ratio and fluid properties. The friction constants deduced by theoretical analysis are consistent with experiment results, and the pulsating amplitude of friction constant will become large as the pulsating period becomes short or the relative amplitude becomes large.