To achieve safe and efficient coordinated mining of upper and lower coal seam working faces, taking the engineering background characterized by "thin upper seam and thick lower seam dominated by weak interlayer rock mass" formed by Working Face 2131 in No.2 Coal Seam and Working Face 5131 in No.5 Coal Seam of Jiaojiazhai Mine, theoretical analysis and physical similar simulation methods were comprehensively adopted, and the dynamic evolution mechanism of overlying rock structure during coordinated mining of upper and lower coal seam working faces was revealed. The research results indicated that the strata behavior of Fully Mechanized Caving Working Face 5131 in No.5 Coal Seam could be divided into three characteristic stages according to whether the intermediate key stratum was completely fractured and connected. In the initial mining stage, the main control rock strata were not fully fractured, and the overlying strata collapsed in layers. The working face presented periodic weighting with small weighting interval and mild intensity, which was mainly induced by periodic fracture of the "cantilever beam" structure formed by the main roof. When the mining advance reached the position where the intermediate key stratum was fully fractured, the goafs of the two coal seams were connected, which destabilized the stable "pressure arch" structure in the upper goaf, activated the overlying strata and caused large-scale cutting-off failure. After the connection of goafs of upper and lower working faces, the strata behavior of the lower coal seam working face entered a stage with increased weighting interval, and the weight of overlying strata was transferred to the lower working face at this stage. The offset distance between upper and lower working faces during coordinated mining was the critical factor affecting strata behavior. This study provided important theoretical basis and engineering guidance for safe and efficient mining of working faces under similar geological and mining conditions.