The water-based nanofluids have good adaptability, and can enter reservoirs with low permeability and play a unique role. Silane coupling agent was used to modify nano-silica, and functional nano-silica fluid dispersion (0.05 wt% modified nano+0.01wt% APE-X) was prepared. Dynamic light scattering particle size analyzer was used to analyze that the modified nanoparticles were mainly concentrated at 20-30 nm, and the dispersions were clear and transparent. The properties of nano-fluid dispersion were investigated by wetting adsorption test, pressure-lowering and injection-increasing, and physical simulation of infiltration. The results show that modified nanoparticles can be dispersed and adsorbed on the wall of rock, thus changing the wettability of rock, and the "slip effect" promotes the injection of fluids into micro-channels. Nanofluids can effectively reduce injection pressure when the injection volume is less than 0.3PV, and the highest pressure drop rate is 34%. The nano-dispersed liquid after entering reservoir has higher oil displacement ability than conventional surfactant.