The present invention discloses a method for preparing a super absorbent resin including the following steps: 1) adding an inner-crosslinking agent, an active promoter, and an initiator to a solution of an unsaturated monomer in water, deoxygenating by bubbling nitrogen therethrough, and then undergoing free radical polymerization to obtain a gel; 2) reacting the gel with a neutralizing agent, extruding, and granulating to obtain a product; 3) drying, pulverizing, sieving, and fixing the particle size combination of the product to obtain powdered raw particles; 4) adding a surface crosslinking agent to the powdered raw particles and performing surface crosslinking by heating to obtained crosslinked particles; and 5) subjecting the crosslinked particles to anti-caking treatment to obtain a super absorbent resin.