Abstract: In order to improve the top coal recovery rate of the thick seam in Carboniferous System of Tashan Mine, the numerical analysis, similar simulation analy sis, site measured statistical analysis, industrial trial and other method were applied to study the key mechanical mining height and top coal caving technology in fully m echanized top coal caving mining technology with the high mining height. The study and practical results showed that under the geological and mining conditions of No.8 105 coal mining face in Tashan Mine, the rational mechanized mining height was 4.04 .3 m, the rational top coal caving step distance was 0.8 m per cutting and caving a nd the rational top coal caving way was multi round interval sequence and multi window caving.