[Objective] In order to create an excellent water-holding material, using wheat straw as raw material, acrylic acid(AA) as graft monomers, the N, N'-methylene bisacrylamide as crosslinker and the potassium peroxydisulfate as free radical evocating agent, the super absorbent polymer was prepared by water solution polymerization. [Methods] The optimized reaction conditions were determined based on a single factor and an orthogonal experiment. In addition, the absorbency, retaining capacity and surface morphology of the obtained water retention agent in the experiment were characterized. [Results] Optimal reaction conditions were as follows: temperature 70 ℃, deionized water 160 ml, 2%N, N-methylene double acrylamide solution 9 ml, initiator accounted for acrylic monomer 2%, degree of neutralization of AA was 70%, reaction time was 1 h. Under this experimental conditions, the water retention agent had stronger water absorbency, and the 1 g dry super absorbent polymer can absorb water 41.2 g/g in 0.9% NaCl solution and 430.9 g/g in distilled water. The colloid graft polymerization of water retention agent was successful, and the surface morphology was good. [Conclusion] Super absorbent polymer has faster fluid and good characteristics of water retention and reuse. The product can absorb water 113 g/g in ferric chloride solution of the different ions solution and the maximum water absorption was 57 g/g in compound ion solution.