The invention discloses a water-soluble vitamin E derivative modified fat-soluble anti-cancer drug compound having a structure of the following formula I or II. An active part camptothecin or camptothecin derivative of the anticancer drug and a lipophilic part water-soluble vitamin E ester or amide are covalently combined by a linking group to form the fat-soluble anti-cancer drug compound. The invention also relates to a preparation, a preparation method and application of the drug compound.