Neoproterozoic magrnatic rocks are widespread on the western margin of the Yangtze block, and their genesis and tectonic setting have long been problems of hot debate. Petrological, geochemical and Sm-Nd isotopic data are reported for Neoproterozoic margin of the Yangtze block. This paper deals Kangding-Danba mafic dykes in the Kangdian rift on the western with petrogenesis and magma source characteristics of these rocks. The rock samples are of tholeiite series, and their geochemical and Nd isotopic characteristics suggest that they were generated in an intraplate setting with variable degrees of contamination of young island arc crust during magma ascending. The magma was generated by partial melting of DM mantle source region within the spinel stabihty field, and was probably related to Neoproterozoic plume event related to the breakup of Rodinia supercontinent.