The northeastern(NE) Tibetan Plateau is an ideal place for the study of plateau uplift and evolution. Its lithosphere records the process of the lithospheric deformation transforming from the Tibet to the stable Alashan and Ordos blocks. Here, using the dense passive-source seismic profile across the NE Tibet and the regional seismic networks of Gansu and Qinghai Provinces, we isolate S receiver functions from the teleseismic S and SKS wave data and resolve the spatial distribution of the lithosphere-asthenosphere boundary(LAB) across the NE Tibetan Plateau. Our observations demonstrate that:1) Beneath the northeastern Songpan-Ganzi terrane and the West Qinling orogenic belt, the LAB lies at 110~130 km which dips at a shallow angle to the northeast, and none lithospheric offset is observed beneath the East Kunlun fault. The smooth LAB may indicate an intact lithosphere between these two blocks; 2) The lithospheric thickness is 135~150 km beneath the Qilian block, and the LAB phases are dispersive beneath the Qilian orogenic belt, in the western part of the Qilian block. The dispersive LAB phases may imply a complex tectonic lithosphere; 3) The LAB of the Alashan block lies at 130~150 km, which seems to converging beneath the Qilian block, but dose not across the Haiyuan fault, yet; 4) The lithospheric thickness of the Ordos block is 160~170 km, which imply a thick and rigid craton lithosphere.