The invention discloses a method for preparing fish protein powder rich in fishskin collagen from a fishskin raw material which contains fish scale, fish fins, fish bone and a small amount of fish meat. The method comprises the following process steps: soaking in salt and alkaline solution, soaking in deionized water for desalination, stirring, modifying in microwaves, degrading complex enzyme at constant temperature, boiling, decolorizing, deodorizing, concentrating and drying. Concretely, the method comprises: transferring a fishskin raw material to salt and alkaline solution which contains 1 percent of NaCl and 1 percent of Na2CO3 and of which the weight is 10 times that of the fishskin raw material, soaking the fishsikn raw material for 12 hours, then soaking the fishskin raw material in deionized water, and washing the fishskin raw material till the pH value of the fishskin raw material is 7; draining, grinding in a meat grinder, adding deionized water in an amount which is 3 times that of the grind material, heating to the temperature of 55 DEG C, keeping the temperature constant, adding neutral protease in an amount which is 0.125 to 0.225 percent based on the weight of the fishskin raw material, and reacting for 0.5 hour under the action of microwaves at a power of 1,000 W; cooling to 45 DEG C, adding bromelain in an amount of 0.0258 to 0.125 percent based on the weight of the fishskin raw material, and continuing microwave treatment for 0.5 hour; and boiling and modifying for 0.5 hours, decolorizing by active carbon for 30 minutes, filtering with aid from kieselguhr, concentrating under reduced pressure, drying and obtaining fish protein powder. The protein extraction rate is more than 95 percent, the product is white powder, free from fish smell and rich in fishskin collagen, the average molecular weight of the product is less than 6,000Da, and the product can dissolve in water instantly.