There are legacy many types of coal pillars during mining the Jurassic coal seams in Datong mining area，that have important influences on strata behavior of underlying carboniferous coal seam. The condition of forming inverted trapezoid island structure in overburden structure is determined by analyzing structural characteristics of legacy stacked coal pillars in Jurassic coal seams using the method of ratio discrimination for multi-coal seam mining and limit equilibrium theory，the mechanical model of inverted trapezoid island structure is established and the quantitative influence of different sizes of stacked coal pillars to the coal seam of underlying carboniferous is analyzed. The theoretical analysis shows that the inverted trapezoid island structure leads to the stress field of carboniferous coal seam increasing 91%–259% than in-situ stress field when the width of coal pillar is between 30–120 m，and the influence of inverted trapezoid island structure to carboniferous coal seam become maximum when the width of coal pillar is 80 m or so. The microseismic monitoring shows that the microseismic events have a large distribution density and with higher energy levels(10⁶ J) when the 8104 working face of carboniferous coal seam through the area of stacked coal pillars. The theoretical analysis and field monitoring have good consistency and the research results can provide a theoretical support for the roof management and dynamic disaster prevention etc when Carboniferous coal seam through Jurassic legacy large coal pillar.