In order to improve the utilization rate and economic benefit of lignocellulose, the hydrolysis of corncob was studied by the method of using dilute acid as catalyst under microwave irradiation. Through single factor and orthogonal way ,the influences of microwave radiation time, microwave power, acid concentration, solid-liquid ratio and particle size of corncob were discussed with sugar yield and raw material conversion rate as index ; Raw materials and three methods of treatment of hydrolyzed residue were analyzed by scanning electron microscopy (SEM) and infrared spectroscopy (FT-IR).The results showed that the optimal reaction conditions were as follow: corncob was crushed to 60～80 mesh, the solid-liquid ratio was 18 (g/mL), the acid concentration was 13%, the microwave power was 130 W, and the reaction time was 20 min. At this time the yield of reducing sugar was 66.41%, the conversion rate of raw materials was 52.70%. SEM and FT-IR analysis showed that the effect of microwave acid was good, and the surface structure of the corncob after the reaction was seriously damaged. In the corncob hydrolytic residue of microwave radiation and dilute acid catalyzed, the hemicellulose was completely hydrolyzed, and some of the cellulose was hydrolyzed.