This work present polystyrene nanoparticle, a new nanoparticle that is non-conductive and less expensive. Polystyrene nanoparticle added to water based drilling fluid design and tested for filtration loss at Low Pressure Low Temperature (LPLT) condition (25°C and 100 psi) and High Pressure High Temperature (HPHT) condition (150°C and differential pressure of 500 psi). In comparison to based fluid design, polystyrene nanoparticle added drilling fluid reduced filtration loss by 29%. While in comparison to base fluid and polymer drilling fluid, the polystyrene nanoparticle added drilling fluid reduced filtration loss by 50.7% under LPLT condition. Under HPHT condition, polystyrene nanoparticle added drilling fluid reduced fluid loss by 44.4% in comparison to base fluid. While in comparison of base fluid, polymer and polystyrene nanoparticles reduced fluid loss by 61.1%. Polystyrene nanoparticle drilling fluid formed a thin non-erodible low permeability filter cake, this showed that polystyrene nanoparticles plugged the pores of the filter cake. Thus, it can be concluded that polystyrene nanoparticle improved filtration control of water based drilling fluid.