Abstract: In this paper, the hydrophobic temporary plugging agent HTPA-1 with good performance was developed according to hydrophobic temporary plugging theory. Its size distribution, morphology, contact angle, oil dispersity, viscosifying effect and surface adsorbability were investigated by means of light scattering, SEM (scanning electron microscope) and absorption capacity test. It is shown that HTPA-1 has stronger hydrophobic property and better oil dispersity with contact angle of 81°-165°. It presents a certain viscosifying effect with grain size of 900 nm. It is capable of decreasing the surface tension to 40 mN/m at most. When the clay-free polysulfonate drilling fluid was added with HTPA-1, its oil phase breakthrough pressure decreased over 70% and water phase breakthrough pressure doubled. Obviously, HTPA-1 plays an important role in water confining and oil communicating.