The palaeoplate evolution in the southern part of the Inner Mongolianorogenic belt can be tentalively concluded as follows on the basis of studies ofthe petrotectonic assemblages, structural sequence, and isotope dates of someimportant rocks in the past five years. The northern margin of the North Chinaplate probably developed from continental rift to passive continental margin inthe Middle Proterozoic. It began to transform into the active continental marginin the Late Proterozoic and by the Early Paleozoic, it began to be subducted andslipped sinistrally. The southern area of the Inner Mongolian orogenic beltunder-went isostatic uplift and faulting twice, following the emplacement of the OndurSum ophiolite. The North China and Siberian plates were sutured in the terminalHercynian and then the evolution of the orogenic belt entered a stage of ultraco-Ilision, when a vast amount of granite intruded and a series of nappe structureswere formed.