Abstract: Based on the actual comparison difficulty of the high thickness variation in Turpan－Hami Basin，in order to seek the obvious the new different characteristics applied to compare the seams，a coal petrology method was applied to the analysis study on the coal facies of the seam in Sandaoling Section of Turpan－Hami Basin．The study results showed that the genetic parameters of the seam in Xishanyao For- mation of Sandaoling Section were high in the vitrinertite ratio．The tissue preservation index and the vegetation index were low．The gelifica- tion index was all higher than 1．The coal facies type was a wet vegetation type mixed peat swamp，including three subclasses of the peat swamp I type，the peat swamp II and the peat swamp III type．Among them，the peat swamp II type coal facies would have very high gelifi- cation index and vitrinertite ratio and the underground water flow index would have the lowest features．The hydrodynamic condition from the top to bottom of the seam would have the variation from weak－enhancement－weak and the water covering depth of the seam would be changed from the deep to shallow．The coal facies features of the peat swamp II was obvious and could be applied to the comparison of the seams in Turpan－Hami Basin．