Abstract: In order to solve the problem that conventional water-based drilling fluids could not meet the needs of complicated deep well during explorating and developing, based on the development of anti-high temperature surface hydration inhibitor and nano-plugging agent, the high temperature resistance and anti-sloughing water base drilling fluid system with density up to 2.0 kg/L was established through the optimization of other additives and their ratio. The mud had good temperature resistance(up to 220 ℃) and excellent contamination resistance(3.0% bentonite cuttings tolerance and 0.6% calcium tolerance ),whose density difference between up and down is only 0.02 kg/L after 96 hours, inhibition and lubrication performance was similar with oil-based drilling fluid, and plugging rate of tight sandstone was 85.6%.The field application result showed that the drilling fluid system still maintained good lithology-carrying property, prominent borehole stability and excellent lubrication and drag reduction performance in high temperature deep wells, which provided technical support for exploration and development of deep and ultra-deep wells in complex formations.