The determination of sedimentary timelimit of Chengjiang Formation plays very important role in stratigraphic division, correlation of Neoproterozoic strata and reconstruction of paleocontinent in Southern China. Magmatic zircons from tuff interlayer in the middle of Chengjiang Formation in Qiaojia area, northeast Yunnan Province, were selected to carry out high-precision SHRIMP U-Pb chronological study. Two sets of effective weighted average 206Pb/238 U ages of (785±12) Ma and (828±8.3) Ma were obtained. Therefore, the two weighted mean 206Pb/238U ages are the records of two episodic magmatic activities related to the split-up of Rodinia.