The invention discloses a method for extracting chitin from grub adult Holotrichia parallela, comprising the following steps: 1, drying and grinding; 2, removing inorganic salts and other impurities; 3, removing protein and other impurities; 4, conducting oxidative decolorization, and 5, preparing a purified product of chitin. According to the invention, the method uses agricultural insects as a raw material, has the advantages of simple process and convenient operation, realizes the recycling of resources; and the appearance color and physical and chemical indexes of the prepared chitin meet the criteria for the application in the industries of food, medicine, cosmetic, agriculture and environmental protection and the like.