Abstract:   To effectively control the coal wall stability of fully mechanized working face in “three soft” coal seam，we measured the characteristics of coal wall falling at NO.7₂19 fully mechanized face with great mining height in Xutuan Coal Mine of Huaibei Mining Group，built the mechanical model for stability analysis of wedge sliding object in coal wall，and analyzed the key effect factors of the sliding object stability．The results show that the coal wall falling in fully mechanized face with great mining height in “three soft” seam occurs mainly in wedge sliding type in the upper part of coal wall，and the stability coefficient of wedge sliding object (K) is proportional to C，P_h and μ， and inversely proportinal to W₀ and θ．By adopting technical measures of increasing the support resistance，controlling end face roof fall, strengthening coal wall，correctly using guard plate，appropriately increasing the advancing speed，et al，the coal wall stability of NO.7₂19 face has been effectively controlled．

Key words: three soft coal seam, fully mechanized mining with great mining height, coal wall stability, wedge sliding object, control technology