To improve the unfavorable engineering performance of sand and make it applicable for riverbank slopes， foundation， and road reinforcement， a method for modifying sand using polymers and fibers is proposed. Through unconfined compressive strength tests and numerical simulations， the strength characteristics and deformation failure modes of the modified sand are analyzed. The results indicate that the combined use of polymers and fibers can effectively enhance the compressive strength of sand， and the compressive strength of the modified sand increases with the dosage of polymers and fibers. The maximum compressive strength of the modified sand is 414.53 kPa， with the optimal recommended dosages of fibers and polymers being 0.6% and 4.0%， respectively. The addition of fibers forms a force chain network in the sand， thereby increasing the stress transmission paths and effectively delaying the development of micro-cracks within the sand. The incorporation of polymers creates a membranous substance that intertwines with the fibers， forming a new network structure， which significantly improves the deformation resistance of the sand.