Abstract: Taking the mining of thick coal seams with thin bedrock and thick loose layers in the Xinqiao Coal Mine as the research background, this study investigated the movement law of overlying strata in such geological conditions through a combination of similarity simulation, field measurement, numerical simulation, and theoretical analysis. A composite structure of loose layer arch and pseudo-plastic rock beam was proposed, and mechanical models for overlying strata rupture and support resistance calculation in working faces were established. The main conclusions are as follows: Under thin bedrock and thick loose layer conditions, the bedrock located in the weathering-oxidation zone exhibits low strength, leading to reduced self-stabilization capacity and bearing capacity of overlying strata. This results in extensive caving zone development and a characteristic "high static pressure - low dynamic pressure" continuous pressure phenomenon in support resistance. The structural evolution of overlying strata undergoes four stages: main roof fracture, pseudo-plastic rock beam formation, loose layer caving arch development, and lateral expansion of caving arch. Before pseudo-plastic rock beam formation, support resistance mainly originates from collapsed rock mass; afterward, it combines static load from caved rocks and given deformation of pseudo-plastic rock beam. Numerical simulations analyzing force chain distribution and stress patterns reveal that the bearing range of pseudo-plastic rock beams does not encompass all overlying collapsed strata. The mechanical transmission mechanism between loosened rock masses effectively reduces the actual bearing range. Crack propagation demonstrates two dominant mechanisms: deviatoric stress tensor control and soil arching effect. Based on fracture mechanism analysis, a mechanical model for overlying strata rupture was established. The derived hydraulic support resistance formula shows good consistency with field monitoring data. This research provides theoretical references for support selection and roof control in fully mechanized mining faces with thick loose layers and thin bedrock. The findings summarize the dynamic evolution laws of the "beam-arch" structure in geological formations characterized by thick unconsolidated layers and thin bedrock. This research can provide theoretical references for support selection and roof control in fully-mechanized mining faces with similar geological conditions in China.