Acrylic acid was used as modifier to prepare a kind of hydroxyl terminated core-shell particles in aqueous phase. Its physic-chemical structure was analyzed by infrared spectroscopy, thermal analysis, scanning electron microscopy and contact angle instrument. The results show that the modified PS particles have an average diameter of 250 nm and its hydrophilic is improved by the surface carboxyl.Product particles were dispersed in the polyethylene glycol 200 through the experiment of highenergy ball milling method so that a new organic polymer shear thickening fluid (STF) was got. The shear thickening behavior was tested by the dynamic rheometer and diffusion spectroscopy. The data of the two tests indicate that the fluid has significant shear thickening characteristics.