Corn with high moisture content in Huang-Huai-Hai region of China had a high moisture when it was harvested, which caused high broken rate and un-threshing rate when mechanical harvesting and restricted the development of corn grain harvest. There were many current studies on corn threshing process at home and abroad. But most studies were on the structure of corn threshing machine. Based on the threshing system of axial flow corn threshing device, through the theoretical analysis of working process of spike-tooth, a kind of curved spike-tooth was designed and optimized to solve the problems. The distinct element method (DEM) was a numerical simulation method for dealing with discontinuous medium problems, which was widely used in the field of bulk material processing. Enhanced distinct element method（EDEM）software was a general computer aided engineering (CAE) analysis software based on the DEM, which was commonly used to simulate and analyze particle processing and operating system in industry and agricultural production. The discrete element simulation model of threshing process was established by using discrete element software EDEM, and the normal force and tangential force of trapezoid spike-tooth and curved spike-tooth were determined by studying the mechanism. The simulation result showed that the tangential force of trapezoid spike-tooth and curved spike-tooth was 24.47N and 20.65N, respectively, and the average force of normal force was 50.93N and 45.47N, respectively. The threshing test was compared with the traditional trapezoidal spike-tooth with different materials. The result showed that breaking rate of Q235 trapezoid, Q235, NBR and polyurethane rubber was 10.23%, 9.84%, 8.03% and 8.35%, and un-threshing rate was 0.53%, 0.92%, 0.77% and 1.02%, respectively. The corn breaking rate was 20% lower than that of the traditional nail, and un-threshing rate was no more than 1.02%. The single factor test was carried out with the factors of roller speed, threshing clearance and feeding amount as factors. Zhengdan 958 with grain moisture content of 28% was set as test material. When using NBR nailed teeth, the feeding amount of corn ear was 10kg/s, the threshing clearance was 55mm, the drum speed was 300r/min, the threshing results showed that breaking rate and un-threshing rate was 8.03% and 0.77%, respectively, which had the best threshing effect. The threshing roller was divided into four sections along the axis, and the distribution of the number of falling corn and corn breaking rate in the threshing test were analyzed. The results showed that the first two sections of the drum were the main threshing area of fruit spike, and the amount of falling grain was about 80% of total grain quantity, and the first section of drum was larger in the threshing of the fruit ear, and the corn breaking rate was the highest. The design of the curved spike-tooth not only had reasonable structure but also the material of spike-tooth was easy to replace and the threshing effect was good. It provided a reference for the design of spike threshing device in the case of high water cut.