Dual drag reduction mechanisms of water-based dispersion with nanoparticle is proposed. A contrastive study is take to verify the mechanism, in which the changes of surface microstructure and wettabilities of the core slices take place before and after treating by dispersion with hydrophobic nanoparticles and scouring by water. The results show that the surface of core slice which is treated by water-based dispersion with hydrophobic nanoparticles has strong hydrophilic property, and a compact nanoparticle adsorption layer forms on it. The nanoparticle adsorption layer still exists after scouring, but the core slice surface is changed into strong/super hydrophobic, reflecting that the surfactants which are adsorbed on the nanoparticles adsorption layer surface are gradually cleaned. The water-based dispersion with hydrophobic nanoparticles are mainly manifested as the chemical surfactant drag reduction effect during initial injection. With the injection continued, the mechanical drag reduction induced by the slip effect of super hydrophobic surface is reflected mainly. Core displacement results show that the water-phase effective permeability could increase about 84.3% on average. The results strongly confirm the dual drag reduction mechanism of the water-based dispersion with hydrophobic nanoparticles.