Cationic starch was prepared from maize starch, with 3-chloro-2-hydroxypropyltrimethyl ammonium chloride used as cationic reagent, by our specific solvent process, which was different from dry procedure. In conventional solvent process, the solvents were hydrophilic and sodium hydroxide was employed as catalyst. Metal sodium as a substitute for sodium hydroxide in the synthesis of high DS (degree of substitution) cationic starch could be obtained using dioxane as solvent. A L9(34) orthogonal analysis was used in this work and results suggested the best combination of the reaction condition was A2B2C1, where the reaction time, temperature and weight of metal sodium were 2 h, 80 °C and 0.5 g, respectively. FTIR spectra revealed a special peak (1450 cm-1) of cationic starch confirming the existence of cationic groups in cationic starch. In a model of neutralizing the anionic groups, it revealed that the content of 0.8% (w/w) cationic starch was the optimum dosage.