The Tanjianshan Group is widely distributed on the margin of the Qaidam basin, the Tanjianshan Group on the northern margin of the Qaidam basin composed of intermediate-basic volcanic rocks, classic rocks and carbonate rocks, whereas it composed of classic rocks , carbonate rocks, with small intermediate-basic and intermediate-acid volcanic rocks in East Kunlun (the southern margin of the Qaidam basin). The isotope geochronology and geochemical of basalts from the Tanjianshan Group are reported in this paper. previously the basalts in the northern margin of the Qaidam basin were formed between 510 and 460 Ma, LA-ICP-MS analyses that the zircon grains from basalts in East Kunlun have concordant U-Pb ages of (455 ± 13)Ma, the regional mapping of East Kunlun indicates the basalts were formed at 440Ma, so we consider these formed middle-Ordovician to early Silurian. Geochemical characteristics of basalts in the northern margin of the Qaidam basin indicate the tectonic attribute of an volcanic arc, the basalts in East Kunlun have similar geochemical characteristics to E-MORB lavas, which represent the remnants of fragmented oceanic crust of the Paleo-Qimantege ocean.