Abstract: On the studies of the occurences, compositions and geochemical characteristics of the tonsteins in middle of Ningwu-Jingle Basin, We found the positive correlations between elements of Nb,Zr, (K + Na +Ca) and TiO₂ and the contents of kaolinite, discussed the probable sedimentary and spreading mechanisms of fine-grained sediments in swamp,as well as proposing the view that the local tonsteins were formed by leaching and concentration of the weathering products of medi-acid igneous rocks of Yinshan palaeoland which were transported and sedimented in swamp.