In order to develop a new preparation method of starch acetate,the cassava starch acetate was synthesized by mechanical activation-strengthened solid phase chemical reaction.The effects of acetic anhydride content,sodium hydroxide content,ball-milling temperature,ball-milling time,stirring speed and the volume of the stack for ball-milling media on esterification of cassava starch were investigated.The degree of substitution(DS) of starch acetate was used as the evaluating parameter.The best conditions of preparation technique were confirmed by orthogonal test.The optimum conditions of cassava starch acetate preparation were 60% acetic anhydride,2.0% sodium hydroxide,ball-milling temperature 60℃,ball-milling time 60min,stirring speed 380r / min,tack media 500 mL,the DS of the products 0.2632,and the RE was 25.57%.Furthermore,the structure of native starch and the starch acetate were further characterized by using Fourier transform infrared spectrometry(FTIR) and X-ray diffraction(XRD).The mechanical activation considerably enhanced the esterification of cassava starch.