The invention relates to the field of synthesis of polymer materials and discloses a preparation method of sodium polyacrylate water-absorbing fibers. The preparation method comprises: A) preparationof organically modified vermiculite powder: adding lactose and dodecyl dimethyl benzyl ammonium chloride into water, carrying out heating for a reaction, carrying out reduced pressure distillation, cleaning the product, drying the product to obtain modified lactose, calcining and grinding vermiculite, preparing a suspension liquid, carrying out heating, adding the modified lactose into the suspension liquid, carrying out stirring under thermal insulation for a reaction, and carrying out centrifugation, filtration and drying, B) neutralization: adding acrylic acid and acrylamide into water, andthen neutralizing the solution with sodium hydroxide until the pH is 5-5.5, C) polymerization: adding organically modified vermiculite and bacterial cellulose into the solution, and adding a triallylammonium chloride and an initiator into the solution for a reaction so that a viscous liquid is obtained, and D) wet spinning: preparing sodium polyacrylate fibers. The organically modified vermiculite powder in the sodium polyacrylate fibers can effectively improve the strength and aging resistance of fibers.