Abstract: δ-aminolevulinic acid(ALA)-based photodynamic therapy(PDT)is a noninvasive topical treatment choice that can selectively kill target cells.One important mechanism for its therapeutic effect is to intluence some biological characteristics of target cells.Besides nonpigment cell malignant tumors of skin,ALA-PDT could be used in the treatment of premalignant lesions,viral warts,acne,connective tissue diseases,actinic skin diseases,and SO on.Appropriate higher temperature,cosolvents,metal chelating agents.iontoplaoretic delivery and liposome vector may enhance the therapeutic efrect of ALA-PDT.