Different perspectives exist in the structural attribution of Langshan, western Inner Mongolia.No direct evidence pointing this region belonged to North China Craton has been found. In this paper, detailed chronology study is applied to Biotite Plagiogneiss (garnet- contain) from Bayinqiandamen, Langshan, Inner Mongolia. According to the result derived from LA- ICP- MS U- Pb isotope dating, all samples were magmatic zircon, 1946±9Ma and 1918±11Ma indicating the crystallization age of protolith. This result proved magmatism occurred in Langshan in the late stage of Paleoproterozoic era. According zircon Hf isotope, epsilon Hf(t) ranges from -1.3 to 6.4.The Hf isotope source area contains both North China Craton’s basement material and contribution from mantle. The model age of 2442Ma indicates that the source rock originated from the early Proterozoic crustal accretion event, which may be related to the formation of North China craton basement. Therefore, similar to central North China Craton, this region also contained Magmatic from early Proterozoic. The study of detrital zircon in Baoyintu Group as well implied the affinity between Baoyintu Group in Langshan and North China Craton, suggesting Langshan structure should belong to North China Craton.