The “frozen-in” information in the crust plays an important role in improving our understanding of cratonic formation and evolution and plate tectonics in the Precambrian. The Trans-North China orogen is a continent-continent collision belt generated by the assembly of the North China craton. The mechanism and modality of the collision are disputed. Here we present a seismic image of the Western block and the Trans-North China orogen of the North China craton derived using receiver function analysis of the teleseismic records from a dense array. A low-velocity zone extending from the middle crust to the Moho is interpreted as a remnant of upper-middle crustal material associated with westward-dipping subduction beneath the Western block of the North China craton. Crustal uplift and magmatic underplating resulting from subsequent tectonic events were responsible for modifying the remaining subduction architecture. The western boundary of the Trans-North China orogen is located west of the boundary earlier identified by surface investigation. The results, combined with previous seismic imaging in the eastern North China craton, provide insight into the amalgamation of the Eastern and Western blocks and the subsequent tectonic deformation of the North China craton.