Abstract: Experiments were made to investigate the flow pressure drop and the friction coefficient of the kerosene(RP-3) in micro tube.The result shows that the friction coefficient decreases with the increasing Reynolds number,and the friction coefficient in micro tube is smaller than in traditional channels;the critical Reynolds number of flow from laminar to turbulent in the small tube is much smaller than 2300 in conventional ducts.In addition,the pressure drop increases with the increase of Reynolds number;under the same Reynolds number and same tube length,the bigger tube inner diameter means the smaller pressure drop between the inlet and outlet;the smaller tube inner diameter means the bigger pressure drop between the inlet and outlet.