Abstract: The middle Proterozoic Shuangqiaoshan Group in area of Mufu and Jiuling Mountains，Northwest Jiangxi is a set of normal sedimentary strata with obvious sequence and is covered by the Sinan with an unconformity．The nearly N folds formed early were modified by the nearly E W folds and synchronous tectonic heat fluid event which is the intraplate trace of the collision between the Yangtze and Cathaysia plates ． The intraplate tectonics and amalgamation belt occurred in a synchronous tectonic movement．K-Ar dating of single mineral of diorites from the Manjiang and the Shanko units which intruded into the E—W folds give ages of 846±7 Ma and 805±75 M a respectively． The palaeo-faults are the companions of the E-W folds． These evidences suggest that the tectonic deformation occurred in the Precambrian before 800 Ma corresponding approximately to the Grenville movement and the existence of the Jiangnan Ancient Land．