The present invention provides a cationic arabinoxylan and the hydrophobically modified product thereof. The cationic arabinoxylan is prepared based on a cereal arabinoxylan and a quaternizing agent, with water as solvent and strong alkali as catalyst. The hydrophobically modified product is prepared based on cationic arabinoxylan and alkyl halide, with pyridine as catalyst. Said cationic arabinoxylan and the hydrophobically modified product thereof can be used as a conditioning agent or thickener in cosmetics or personal care compositions, and can also be used in textile, papermaking, pharmaceutical and food industry applications.