<p>In response to challenges posed by low human efficiency and dust health risks in grain storage operations, the implementation of automated grain silo robots has been pursued. However, in actual flat grain operations, robots often underperform because of their limited performance, high energy consumption, and speed constraints. This study aimed to explore the mechanism underlying the interaction between a grain silo robot and corn particles by employing a discrete element method (DEM)–multibody dynamics (MBD) co-simulation method to construct a coupled model from a mesoscopic perspective. The model was used to analyze the variation laws of the motion velocity, sinkage, slip rate, and pitch angle of the grain silo robot under different working conditions. The results indicate that the motion velocity is positively correlated with the spiral speed but negatively correlated with the drawbar pull and body mass. At spiral speeds over 1.5 r/s, the fluctuation of the motion velocity intensifies with increase in spiral speed. Further, the sinkage decreases with increase in spiral speed but significantly increases with increase in body mass. The slip phenomenon is primarily caused by the longitudinal displacement difference of the spiral wheel; the slip rate is positively correlated with the spiral speed, drawbar pull, and body mass. The pitch angle positively correlates with the spiral speed and body mass, and a moderate pitch angle improves the motion velocity. The findings provide a basis for the engineering design and application of spiral-driven grain silo robots.</p>