Abstract: Abstract: Angle of repose is an important macroscopic feature in characterising the interactions within an assembly of particles. In order to accurately predict the angle of repose of the particle material,a numerical simulation study was applied on the process of particle packing based on discrete element method. In this paper, a simulation model of bottomless cylinder was designed with EDEM software. By taking the rice particles as the example, the physical properties of rice particles, including density, Poisson's rate, shear modulus, coefficient of restitution, coefficient of static fraction, and coefficient of rolling fraction were obtained through the study of some scholars. The shape of rice particle was regarded as ellipsoid. The average value of rice particles' dimension parameters were reported in statistics, namely the long axis is 7.2 mm, and the minor axis is 3.0 mm. According to the shape and the dimension parameters of rice particles, a method for establishing the model of particle based on particles agglomerate was employed, and with the 9 spherical particles agglomerate to approximate real shape grain. In the process of simulation, the cylinder was firstly filled with rice particles. Based on the number and density of particles, the average mass of 43.12 g was calcuated. After being filled with the particles, the cylinder was slowly lifted at a speed of 0.05m/s. Particles flowed from the mouth of the cylinder and formed a stable accumulation under gravity load. In addition, this paper analysed the influence of different lifting speed on the accumulation form.The numerical results showed that, under identical conditions, increasing lifting speed of cylinder led to the rise in diffusion trend of the edge of the grain heap particles. However, when the speed was less than 0.07 m/s, granular pile was formed relatively stably. Meanwhile, this paper obtained the unilateral outline of particle accumulation through MATLAB image processing technology. Then linear fitting was applied to process image contour of rice packing and the angle of repose of rice was predicted in a non-experimental condition. In the end, the discrete element method combined with image processing technology showed that the angle of repose of rice was 22.66°±0.49°. The accumulation of rice particles was verified in the test trial. Under the same condition with simulation, field test result showed the angle of repose of rice was 22.62°±0.33°. In comparison with the simulation result, the error of the repose angle of rice from field test was 0.18%. Therefore, discrete element method and matlab image processing technology could be applied to simulate rice packing in the bottomless cylinder. The result showed that the method which combines the numerical simulation with feature extraction from image has good adaptability for measuring the angle of repose of particle material and can achieve the prediction of the repose angle of particle material on known physico-mechanical parameters.With the improvement of computer tecnology and algorithms, for agricultural particulate materials,the prediction method would bring guidance for the numerical determination of the angle of repose, the study of friction and mobility characteristics and the design of related storage and processing equipments.