Abstract: Corn straw fibers were used as the reinforcement for desulfurization gypsum, through the experimental research on mechanical properties, the effects of different dosages of the corn straw fibers on the mechanical properties of the composite were studied. The results indicate that when the dosage of the corn straw fibers is 5%, compared with the blank sample, the samples flexural strength and compressive strength are enhanced by 92.31% and 7.14% respectively. The corn straw fibers were modified with alkaline treatment and chemical coating treatment using polyacrylamide and acrylic, through the experimental research on mechanical properties and observation on morphology using scanning electron microscopy, the effects of surface modification on the mechanical properties of the composite were studied. The results indicate that the interfacial bonding between the maize straw fibers and desulfurization gypsum is improved, and the mechanical properties of composite is increased. The research shows that the acrylic chemical coating method could enhance the strength of the composite. Compared with the unmodified corn straw fibre/desulfurization gypsum, the flexural strength increases by 55.71% and the compressive strength increases by 22.99%.