In the combined mining of ultra-close multiple seams with thin upper seam and thick lower seam, the mining of thin upper seam may lead to damages of the interburden and collapse of overburden. As a result, the roof of the thick lower seam in the fully mechanized caving process is turned into layers consisting of parts with different medium characteristics, in terms of damage severity and rock size, and the caving and recovery of top coal is significantly affected. Therefore, we propose a study of top coal caving and roof rock movement law under different fracture conditions based on two dimensional discrete element numerical simulation software program. The results revealed that roof rock channeling into the top coal was observed in the coal caving process in the presence of a huge difference between the lump sizes of roof rock and top coal of the lower seam, resulting in low recovery ratio. And the one cut/one caving upward caving pattern was the optimized top coal caving parameter. This study serves as a reference for future studies of top coal recovery in the combined mining of contiguous coal seams with thin upper seam and thick lower coal seam.