Abstract: Considering the status quo of the relatively limited researches and applications of super absorbent polymers (SAPs) in China, two SAPs(SA and SAM) were synthesized by the copolymerization of monomers onto starch through specially designed preparation technology processes. The optimum conditions for obtaining maximum water absorption were determined by orthogonal test method. SA and SAM were characterized by infrared spectra and scanning electron microscope (SEM). The infrared spectra indicated the chemical grafting of pAA and pAM onto starch, and SEM observation showed the porous structure and three dimensional networks of the tow polymers. Both the graft copolymers have desirable water absorption capacity in distilled water and in 0.9% physiological saline. The experiments of soil water evaporation showed that both polymers reduced water evaporation obviously. Higher application amounts produced better effects. The effect of SAM was better than that of SA.