This research aims to solve the problem of material accumulation on the screen surface of the cleaning device of tracked combine harvester and proposes an innovative solution of designing a pre-screening device based on the traditional cleaning device. The problem of material accumulation on the screen surface is improved, which in turn enhances the cleaning efficiency. In this study, CFD-DEM coupled simulation technology is used to simulate and analyse the cleaning device, and the effects of airflow velocity, vibration frequency and amplitude on the cleaning effect are explored, and the impurity content and loss rate are used as evaluation indexes. Through orthogonal experimental analysis, the optimal parameter combination of the cleaning device was determined as airflow velocity 11 m/s, vibration frequency 9 Hz, amplitude 30 mm, impurity content rate 2.10% and loss rate 1.62%. The experimental results show that increasing the pre-screening device can significantly improve the material separation effect, reduce the loss and improve the cleaning efficiency.