Due to the problems of low strength and poor hydrophobicity of starch film, high-amylose corn starch(HACS) was used for modification. In the first place, the molecular chains of HACS (reducing end) were grafted with alkynyl. Afterward, the azide-alkyne click chemistry reaction was used to the graft cationic to obtain a positive charge located at the end of starch chain (TCS). Based on modified starch, starch films were prepared under the action of an external electric field. Finally, the films were hydrophobized with hydroxy silicone oil. The films were characterized by FT-IR, NMR, 2D SAXS, etc. The FT-IR and NMR confirm that the target product (TCS) was synthesized successfully. Combined with the tensile test and 2D SAXS, the results indicate that the molecular chains tend to be oriented with the external electrostatic field. The tensile strength (TS) and contact angle (CA) of the HPHACS/TCS film are increased by 52.5% and 48.2%, respectively. Therefore, this method can be used as a reference for preparing high-strength hydrophobic starch film materials and can extend the application of starch film in packaging materials.