Abstract: Based on the study of zircon SHRIMP U-Pb dating on metamorphic strata in crystalline basement,and supracrustal enclave in orthogneiss in western margin of Yangtze terrane, the ages of 816±8.6 Ma and 826±13 Ma for a mylonitic felsic schist and a biotite amphibolite in the gabbro-diorite gneisses in Kangding area were determined, which are considered as the eruption ages of felsic volcanics and volcanic tuff; The ages of 816±9 Ma and 818±8Ma for a felsic mylonite and an amphibolite in metamorphic strata of Luding area, respectively, were obtained which are also suggested to be the eruption ages of intermediate and basic volcanics; The ages of 830±7 Ma and 827±10 Ma were yieled for an amphibolite and a hornblende biotite plagioclase gneiss in Cida area, which indicate the timing of volcanic-sedimentary association. The above SHRIMP zircon U-Pb chronological results show that the so-called crystalline basement in the western Yangzi plateform is chiefly constructed by Neoproterozoic magmatic rocks corresponding to the Yanbian group and Yanjing group in age, and their difference is only expressed in the metamorphic grade. Therefore, our new chronological evidence do not support the existence of an Archean to Paleoproterozoic crystalline basement in the western margin of Yangtze terrane.