Pickering emulsions were successfully stabilized by highly hydrophilic silica nanoparticles (SiO2 NPs) near the isoelectric points. We found that vigorous mixing of SiO2 NPs suspensions of with oil, van der Waals forces between particles and oil droplets are sufficient to trap SiO2 NPs in close proximity to oil-water interfaces when the pH of suspensions equal to isoelectric points, and O/W Pickering emulsions were stabilized. Increasing the concentrations of SiO2 NPs or decreasing the oil phase volume fractions leads to a higher particle absorbing amount at the oil/water interface, higher viscosity of the continuous phase as well as the formation of a three-dimensional network structure between the emulsion droplets, thereby improving the stability of the emulsions. The emulsions perform good pH responsiveness benefiting from the protonation and deprotonation of silanol on the surface of SiO2 NPs under varying pH.