Abstract: Grafting of acrylic acid (AAc) onto the surface of PTFE micropowders was performed by pre-irradiation method, in order to improve their dispersion in aqueous solution. The effects of various experimental parameters on the degree of grafting (G） were separately investigated, including: volume fraction of AAc, proper addition of concentrated sulfuric acid, mass fraction of inhibitor and reaction time. The result shows that G is increasing with increment of AAc concentration below 50%, and can be enhanced by adding a proper amount of sulfuric acid. Under our experimental conditions, G reached its saturated value when the mass concentration of the inhibitor was 0.8 g/L and the reaction time was 3 h. The introduction of more than 10% of poly(acrylic acid) chain on PTFE micropowders results in the good dispersion of PTFE micropowders in aqueous NaOH solution. 