With isophorone diisocyanate (IPDI) and polytetramethylene glycol (PTMG) as main materials, dihydroxy methyl propionic acid (DMPA) as hydrophilic chain extender, A95 and hydrazine hydrate as small molecule chain extender, a low gloss waterborne polyurethane(WPU) dispersion was prepared by prepolymer dispersing method. The structure and surface of the WPU film were investigated by FTIR,AFM and TEM. Results show that WPU film surface microstructure fit with the extinction mechanism of low gloss. When wBismuth acid catalyst=0.016%,w hydrazine hydrate = 45%, wDMPA = 2.6%, wA95 = 0.84%, the WPU film has a good low gloss performance.