Abstract: Plot breeding has become a key part for the selecting of seed and the preparation breeding program to date, providing for the evaluation data and breeder or original seeds. At present, preserving biodiversity and ecosystem functions have posed a great challenge on the seed mechanization of field experiment in rapidly increasing rural areas in China, particularly on the special agronomic and test requirement. Seed harvesting from the plot is still in manually processing with a simple assistant tool, or by commonly used machines to clean, such as screen separator and air-screen separator with the capacity about 50-100 kg/h. A special cleaning device is lacking for the plot seeds in the modern variety breeding. Technology and equipment of seed cleaning have been a focal issue to efficiently promote the production capacity or quality in a plot breeding. In the special need of seed processing, a novel cleaning treater was systematically designed in this study, thereby to improve the mechanization level of plot breeding. The seed cleaning device in batches consisted of the frame, feeding system, winnowing system, sorting unit, driving unit, and electronic control system. A combined screen with open frame and variant-frequency vibration was used in the device, further to enhance the working quality, such as batch cleaning efficiency and preventing seed mixing, as well as easy operation in screen cleaning. Other main components were also optimized in this study. Furthermore, A Box-Behnken test was conducted, where the seed purity, percentage of chosen seed, and working time were selected as test indexes, while the feeding rate, vibration frequency, amplitude, and screen inclination angle were selected as factors for design. The results showed that the amplitude, vibration frequency, and the interaction between them were significant factors, indicating a strong influence on the seed purity and percentage of chosen seed. The working time greatly depended on the feeding rate, vibration frequency, and amplitude. An optimum combination of selected factors was achieved, where the feeding rate of 0.072 kg/s, the vibration frequency of 6.25 Hz, the amplitude of 5mm, and the screen inclination angle of 4.6°, to reach an optimal design with the seed purity of 98.8%, the percentage of chosen seed of 99.7%, and the working time of 50 s. A performance test was also carried out, indicating that the experimental data was basically consistent with that in the model prediction on condition of 3 kg per batch. The data demonstrated that the processing capacity of the device can be 10 batches per hour (15 kg per batch), where all the indexes can meet the design requirements. This finding can provide a sound reference for the optimal design of batch cleaning device for the seed or other granular materials.