Abstract: In the paper, the sedimentary features of the Carboniferous Taiyuan formation of Tengxian Coalfield has been expounded. The typomorphic characteristics of the main detritel minerals and the differences between muddy-sandy rocks and volcaniclastic rocks in compositions, textures and sedimentare structures have been analysed. It is suggested that there is fundamentally no so-called "Volcaniclastic rocks" in Taiyuan formation of Carboniferous in Tengxian Coalfield. In addition, a view on the nomination of "Volcaniclastic Rocks" has been presented.