Inorganic salts, like ammonium chloride(NH4Cl) and sodium chloride(NaCl), was used to intensify activation of starch, and further to improve methylation of starch with dimethyl carbonate by the help of tetrabutyl ammonium bromide (TBAB).It is showed that the methoxyl content of methyl starch gets to 5.9%, by mass ratio m (starch): m (NH4Cl): m (NaCl): m (K2CO3): m (TBAB)=10:5:5:10:1 and volume ratio v(C2H5OH):v(H2O):v(( H3CO)2CO)=30:10:150, at 55℃ for 1h activation , and 80℃ for 12h reaction.