Castor effluent has complex components, high impurity content and low efficiency after cleaning. There is no special cleaning device. A double-layer inclined vibrating air-screen castor cleaning device was designed. Firstly, the overall structure of the cleaning device was designed, and the double-layer wind blowing synchronous vibration structure was determined. Secondly, the key components of the device, such as vibrating screen, cleaning chamber and discharge port, were designed. The discrete element method (DEM) was used to optimize the structure of cleaning screen. The ZheBi No.4 varieties was taken as the test material, and then the discrete element parameters of the material were measured. Through the single factor test, the effects of the upper screen hole distribution, the screen hole size and the screen surface inclination on the screening efficiency and loss rate were analyzed. The optimum design parameters were determined as follows: the U-shaped mesh arrangement, the mesh diameter of 14mm, and the inclination angle of the screen surface of 8°. The parameters of the single objective function were optimized. When the vibration amplitude of the vibrating screen was 8.43mm, the vibration frequency of the vibrating screen was 6Hz, and the transverse angle of the air flow was 40°, the maximum screening efficiency of castor effluent was 98.20%. When the vibrating screen amplitude was 7mm, the vibrating frequency was 7.76Hz, and the transverse angle of air flow was 40.81°, the minimum loss rate of castor seeds was 2.02%. Through the single factor test, the effects of the distribution form, size and inclination angle of the upper screen surface on the screening efficiency and loss rate were analyzed, and then the best distribution form, size and inclination angle of the screen surface were determined. In order to obtain the optimal working parameters, the coupling method of discrete element method and computational fluid dynamics (CFD) was applied to simulate and analyze the cleaning process. Taking the amplitude, vibration frequency and transverse angle of air flow of vibrating screen as test factors, the screening efficiency and loss rate as test indexes, the ternary quadratic orthogonal combination test was designed. The mathematical regression model between each factor and index was established, and the parameters of the model were optimized. The results showed that when the amplitude of the vibrating screen was 9.00mm, the vibration frequency of the vibrating screen was 6.16Hz and the transverse angle of the air flow was 40.00°, the screening efficiency of the castor cleaning device and the loss rate of castor seeds were the best, which were 97.66% and 2.32% respectively. Through the bench test, the optimal parameter combination was tested. The actual efficiency and loss rate were 93.15% and 6.94% respectively, and the error with the predicted results was controlled within 5%. At the same time, the actual grain impurity content was 0.83%, which met the application requirements. The research result can provide a theoretical basis for the design of castor cleaning device.