Abstract: Disclosed is a method for preparing konjac glucomannan gum. The method includes steps as follows: (1) preparing konjac sol; (2) preparing an amino acid solution by means of L-lysine and L-arginine; and (3) adding the amino acid solution into the konjac sol, and carrying out stirring, standing, and water-bath heating to obtain the konjac gum. According to the method for preparing konjac glucomannan gum in the present invention, the konjac glucomannan is modified by means of the L-lysine and the L-arginine according to a certain ratio, and hydroxyl ions in L-lysine and L-arginine solutions can remove acetyl groups in konjac glucomannan molecules under a heating condition such that thermostable gum can be formed, and properties of the konjac glucomannan gum are improved. According to the present invention, production processes for a konjac gum product are changed, and nutritional functions of the konjac product are added.