Using waste distiller"s grains as raw material, acrylic acid (AA) adjusted the neutralization degree, potassium persulfate (KPS) was used as the initiator, N,N-methylenebisacrylamide (NMBA) was used as the cross-linking agent, 2-acrylamino-2-methylpropanesulfonic acid (AMPS) was introduced as a salt-tolerant monomer, and humic acid (HA) was added, SEM, XRD and TGA were used to characterize and test the microscopic morphology, structure composition and thermal properties of DGC-HA, and the performance indexes of DGC-HA such as water absorption rate, salt absorption rate, nutrient loading rate and release rate, water retention rate and degradation rate were investigated. The results showed that the optimal conditions for the preparation of DGC-HA were as follows: the particle size of dried distiller"s grains powder was 32 mesh, the amount of AMPS was 0.75 g, the amount of HA was 0.4 g, the amount of NMBA was 0.03 g, the amount of KPS was 0.16 g and the neutralization degree of acrylic acid was 50%, and the maximum water absorption rate of DGC-HA was 380.74 g/g, and the saline absorption rate was 45.52 g/g. The water diffusion mechanism of DGC-HA was non-Fick diffusion, and the water retention rates at 20, 40 and 60 °C were 98%, 76% and 50%, respectively, and the recovery rate reached 72% after repeated water absorption for 5 times. The degradation rate of DGC-HA in soil was 39.5% after 30 days. The nutrient loading rate of DGC-HA for ammonium polyphosphate solution at a concentration of 30 g/L was as high as 64.75%, and the nutrient release rate at 72 h was as high as 64.75%. The cellulose and HA in the distiller"s grains were grafted and copolymerized to form a superabsorbent polymer with a three-dimensional network of porous cross-linked structures and surface morphology.