Abstract: In order to improve the production efficiency of cross-linked starch,cross-linked cassava starch was prepared by mechanical activation assisted dry method,and using cassava starch as raw material and sodium trimetaphosphate as cross-linking agent..The effects of sodium trimeta phosphate dosage,sodium hydroxide dosage,reaction time,reaction temperature,rotational speed and stack volume of ball milling media on the cross-linking of cassava starch were investigated using the sedimentation volume as evaluation index. Based on the single factor experiment,the orthogonal test was selected to optimize the process conditions,and the physicochemical properties and structure of cross-linked cassava starch were also characterized and analyzed. The results showed that the best process conditions for the dry preparation of cross-linked cassava starch were as follows:dosage of sodium trimetaphosphate 4%,dosage of sodium hydroxide 2.5%,reaction temperature 40 ℃,reaction time 60 min,rotational speed 380 r·min^-1,stack volume of ball milling media 500 mL,the sedimentation volume of products was 1.52 mL.The cross-linking reaction of cassava starch had been further confirmed by FTIR、XRD、SEM. The transmittance,turgidity,solubility decreased and settlement increased as increasing the cross-linking degree of cross-linked cassava starch. It will accommodate to the development of food industry.