Provided is a photosensitive alkali-soluble resin comprising a compound of formula (I), a method of preparing the same, and a color photosensitive resist containing the same, wherein n1, n2, R1, R2 and R3 are defined as herein. The photosensitive alkali-soluble resin is prepared by: copolymerizing ethylene oxide with α-hydroxyalkyl phenyl ketone to obtain the first intermediate product, followed by copolymerizing the first intermediate product with a copolymerization product of glycerin acrylate, styrene, and maleic anhydride to obtain the second intermediate product, and oxidizing the second intermediate product to produce the photosensitive alkali-soluble resin.