Abstract: Nano-additive is a hot research object in the field of drilling fluids now. When nano-materials are added into drilling fluids,they can control the rheological property, decrease filtration rate, and improve temperature resistance and lubricity of drilling fluids.This paper analyzed nano-materials (e.g. nano SiO2, nano CaCO3, C nano-material and nano-emulsion) in terms of material structure,physical property and chemical property. Then it introduced the working principles and field applications of nano-materials in drilling fluids. Finally, it proposed to build up a mathematical model based on the unique physical and chemical properties of nano-materials to predict the application results of nano-additives and to reduce the cost of nano-additives by means of combination.