The present invention provides an alkali-soluble resin having good developing performance, which belongs to the technical field of polymer material, so as to solve the problem of the poor developing performance of the current alkali-soluble resin and the photosensitive composition made of the same; and a method for preparing the same. In the present invention, tetrahydrofuran groups (flexible functional group) is introduced into the alkali-soluble resin by highly reactive unsaturated monomer, which can improve the developing property of the alkali-soluble resin and can produce a photoresist film with a smooth surface and no corrosion on its side wall.