Abstract: Seeds stratification movement behavior has important application value in agricultural production．To explore stratification movement patterns and key influencing factors for small-sized round seeds, kale seeds were selected as research object．A simulation model was constructed using Discrete Element Method（DEM）to carry out numerical simulation and analysis of kale seeds stratification movement behavior．Impact mechanisms of key parameters, such as vibration frequency, vibration amplitude, and agitator angular velocity, on seed stratification were investigated．Results have shown that angular velocity has a significant regulatory effect on stratification effect．Medium-speed has balanced stratification efficiency and stratification time, low-speed has broken up seed agglomeration but delayed stratification process, high-speed has destroyed stratification stability and intensified particle mixing due to excessive disturbance．Number of agitator rods has affected stratification stability．Stratification effect has been optimal under single-rod conditions, simply optimizing rod spacing has failed to effectively improve stratification performance under multi-rod conditions．Effects of vibration frequency and amplitude on stratification exhibited consistent patterns: the faster frequency and larger amplitude, causing more vigorous seed bouncing, making it increasingly difficult to form a stable stratification structure．Comprehensive simulation and experiments have determined optimal combination of stratification parameters: agitator angular velocity of 45 rad/s, a single stirring rod, vibration frequency of 15 Hz, and amplitude of 1 mm．Under these conditions, stratification rate of kale seeds reached 69.98%．Within same sieving time, seed sieving rate after stratification was 78.7%, while it was only 14% for unstratified seeds．This has confirmed that effective stratification could significantly improve seed sieving efficiency and was core prerequisite for ensuring performance of sieving devices．Research results have provided a theoretical basis and technical support for structural optimization and process parameter regulation of vibration sorting equipment for small-sized round seeds．