Abstract: Flip-flow screens are widely used in dry deep-screening processes across various industrial sectors. However, the influence of the material motion state on the flip-flow screen surface on the screening process remains unclear, which limits further optimization and broader application of flip-flow screens. An experimental platform capable of observing the coupled motion between the flip-flow screen surface and materials is established, and motion tracking of both the materials and the screen surface is implemented based on high-speed photography and target-tracking algorithms. The evolutionary patterns of the coupled motion state between the flip-flow screen surface and materials with varying driving frequencies are investigated. The effects of material load and screen surface tension on the motion patterns of particle groups are analyzed. Furthermore, the influence of different particle motion states on key stages such as material detachment, loosening, and penetration on the flip-flow screen surface is explored. The results indicate that under a material load of 4 kg and a driving amplitude of 6 mm, within the driving frequency range of 1.5 to 15 Hz, as the driving intensity increases, the particle-screen interaction successively exhibits relative static motion, synchronous periodic motion, period-doubling motion, chaotic motion, and inert motion. Among these, the chaotic motion state demonstrates effective disaggregation of moist and sticky materials, and a higher degree of loosening prevents re-agglomeration. The screening efficiency for moist and sticky materials remains below 50% under synchronous periodic, period-doubling, and inert motion states, while it reaches 70% only under chaotic motion. Within the driving frequency range of 6 to 15 Hz, reducing the material load or increasing the screen surface tension can facilitate the onset of chaotic motion in particle groups. The findings are expected to provide guidance for the improved application and optimization of flip-flow screens.