The volcanic sedimentary rocks of the Hangaoshan Group in Lüliang area are representative of Early Masoproterozoic sedimentary records in the Trans- North China Orogen of the Norh China Craton (NCC). The study on their genesis and formation background is of great significance to understand the geological evolution of NCC after the consolidation of the crystalline basement. The volcanic rocks in this group are tholeiite series andesite, with lower SiO2 (54. 68%~56. 19%), higher MgO (4. 97%~6. 16%, Mg#=49. 4~53. 8), Cr (165×10-6~174×10-6) and Ni (31. 1×10-6~34. 2×10-6) contents as well as higher TiO2 (1. 34%~1. 40%), TFeO/MgO=1. 70~2. 03, enriched in LREEs and LILEs (Ba, U and K) and depleted in HFSEs (Nb, Ta and Ti). They show the geochemical characteristics similar to arc magma. However, they have slightly negative εNd(t) with a narrow range of -4. 48~-4. 31. Their TDM is from 2509 Ma to 2520 Ma. Besides, they have high Ba/Th and low (La/Sm)N, indicating that they were derived from the lithospheric mantle metasomatized by plate subduction fluid resulted from the subduction of oceanic plate in the Neoarchean. Furthermore, the volcanic rocks from the adjacent Xiaoliangling Formation, the Xiong’er Group of southern NCC show geochemical characteristics similar to those of arc magmatism, and their Sr- Nd isotopic composition suggested that they were derived from lithospheric mantle modified by the subduction of oceanic plate in the end of Neoarchean. All these volcanics, together with the coeval mafic dykes, were produced in an extensional setting of within plate, indicating that the NCC has transformed into a continental extensional environment in the early Mesoproterozoic, rather than an arc environment magmatism. They are representative of the first volcanic sedimentary after final solidification of the crystalline basement in the NCC, corresponding to the sedimentary products in the early breakup of Colombia Supercontinent all over the world.