Abstract: Response surface methodology was employed to study linked phosphorous(LP) content of phosphate monoester of Canna edulis Ker starch by phosphorylation with monosodium orthophosphate and disodium hydrogen phosphate. The results showed that the molar ratio of NaH2PO4 to Na2HPO4, weight ratio of phosphate sodium to starch, reaction time and pH all had a marked effect on LP content, while the reaction temperature had a less significant effect. And the influence degree of those factors were as follows: molar ratio of NaH2PO4 to Na2HPO4﹥﹥reaction time﹥﹥pH﹥weight ratio of phosphate sodium to starch﹥reaction time. The optimal reaction conditions obtained were NaH2PO4 to Na2HPO4 molar ratio of 1:0.4, phosphate sodium to starch weight ratio of 1.66:1, reaction temperature of 139.86℃, reaction time of 2h and pH of 5.5. LP content experimentally obtained were 0.506%.