There were violent global magmatic activities as immediate areas of research focus for Mesozoic, but few had been reported earlier in Kangdian area, Southwest of China. Through geological mapping in field and laboratory test in recent years in central Kangdian area, a series of Yanshanian mafic dykes were identified in Dongchuan area, Yunnan Province. The SHRIMP U–Pb age for zircons is 128.2±1.5 Ma(MSWD=2.0，n=16), which are highly in accordance with the large scale magmatic activities in the middle and lower reaches of Yangtze River, north China craton, and the golobal pacific superplume events for early Cretaceous. The petrochemistry of Cretaceous mafic dykes are characterized by low SiO2(44.3～47.28%, mean value for 45.68%) and high MgO(6.8～9.64%, average for 7.99%) contents, and high values of Mg#(65.3～70.4, average for 67.9), and Na2O/K2O>1, which are similar to the petrochemistry of tholeiitic basalts. The primitive magma renresented small melt fractions(～1.2%) from garnet-facies combined with large melt fractions(15～20%) from spinel-facies, and experienced slightly crystallization and differentiation of olivine, orthopyroxene and chromite during the evolution. The differentiation of LREE and HREE is not obviously, and the primitive mantle normalized patterns exhibit gently right-dipping curves. The geochemical parameters of trace elements are similar to that of the OIB, and the MORB normalized patterns have no obviously anomaly of high field-strength elements, such as Nb, Ta, Zr, and Hf except the enrichment of Ba and K. The mafic dykes have relatively highly and frequently variational initial (87Sr/86Sr)i ratio(0.71003～0.71499) which may be resulted from the relatively intensively hydrothermal alteration, and the εNdt values calculated according to the U-Pb Age vary from -1.5 to 3.1(average for 2.4) reflecting the actually isotopic composition of primitive magma. The original magma may be contaminated without significant lithospheric material, but probably mixed in more relatively depleted asthenospheric mantle material resulting in high values of εNdt and gentle REE distribution patterns. The genesis of Cretaceous mafic dykes in central Kangdian area maybe have no relationship with the large scale thinning of lithosphere, but may be a branch(the third of more advanced level tectonic unit of mantle plume) of global contemporaneously pacific superplume. Large scale continental flood basalt could not come into being because of the small-scale mantle branch and thick and heavy lithosphere, and the original magma could just only select the tectonic weak belts intruding and then cooling quickly, forming the unique mafic dykes with fine grained texture.