Abstract: By using the refrigerant Ｒ141b as the experimental working fluid，a flow boiling experiment was conducted in the ordinary hydrophilic，super-hydrophilic and super-hydrophobic rectangular micro-channels with crosssectional size of 1mm ×2mm and wall contact angles of 67°，0° and 156° respectively， the pressure of three kinds of surface micro-channel along the measuring point was also compared so as to analyze the pressure drop characteristics of Ｒ141b flow boiling in micro-channels with extreme wettability ( super-hydrophilic and super-hydrophobic) ． The results showed that the ratio of pressure drop components in the extreme wetting micro-channel is approximately the same as that of an ordinary hydrophilic micro-channel，and the friction pressure drop of unit length all increase with the rise of mass flux，inlet temperature and heat flux density; The total pressure drop of microchannels with the super-hydrophobic surface is the maximum，which is 1. 08 ～1. 17 times of the super-hydrophilic surface，and the slope of the pressure curve in the single-phase flow area is the smallest and the slope of the pressure curve in the two-phase flow area is the largest; The Qu-Mudawar model was revised by introducing the surface energy parameter s， the new correlation can better predict the experimental value and the average absolute error is 10. 7%． 

Key words: micro-channels, extreme wettability, flow boiling, two-phase frictional pressure drop, pressure along the measuring point