Abstract: Based on statistical analysis of 1100 Carboniferous-Permian dark mud rock samples in Yingen-Ejin Banner basin, the results about organic matter abundance and source rock pyrolysis show that 50% of collected samples meet the standard of source rock, and superior source rocks occupy over 15%. Vertically, organic matter abundance of mud rock from Carboniferous to Permian (from upper Carboniferous to Amushan /Ganquan Formation in lower Permian , Maihanhada Formation in middle-lower Permian, Aqide/Jushitan Formation in middle Permian to Haersuhai Formation in upper Permian) reveals a trend of gradual decrease. TOC content of northern area is over the counterpart from southern area, and the content of TOC in western part is higher than that of the east, which is coincident with the sedimental environment. In addition, it is necessary to declare that the indicators derived from pyrolysis analysis on outcrop samples ,such as hydrocarbon-generating potential and hydrogen index，cannot be the efficient way to evaluate source rocks.