Abstract In this paper, through field investigation, microscopic analyses of samples of the alkaline plutons, 2 samples zircon LA-MC-ICPMS U-Pb dating and 13 samples geochemical researches, alkaline plutons in the eastern of Dong Ujimqi have been studied, for their chronology and tectonic implications. Alkaline granite and quartz-syenite are the rock association of these alkaline plutons and all show the typical mineral of arfvedsonite. The zircon U-Pb dating suggest that these alkaline granites are formed in Early Permian with detail ages of (272.3±0.7) Ma to (271.7±0.7) Ma. Geochemical researches indicate that the alkaline granites are rich in silica (SiO2＝72.62%～78.46%), alkali (K2O＋Na2O＝7.54%～9.80%) and low CaO (0.66%～0.91%), MgO (0.07%～0.31%), with the character of metaluminous-peralkaline (A/CNK＝0.87～0.99, NK/A＝0.91～1.04). The rocks have moderate REE (146.4×106～389.0×106) , strong Eu depletion (δEu＝0.12～0.36) and low grade fractionation of LREE/HREE [(La/Yb)N 3.74～6.83], with enriched in Rb、Th、U、Hf and depleted in Ba、Sr、P、Ti, which indicate the A1-type granites. Compared with alkaline granites (Ba＝74×106～207×106), quartz-syenites have high Ba (554×106～1230×106) and slightly Eu anomalies (δEu＝0.94～1.24), which maybe induced by the differences of residual minerals as a result of partial melting. Both of them have very low Sr (27.20×106～157.00×106, 2 samples＞100×106) and high Yb (2.08×106～7.26×106, except P24-11-1＝1.36×106), similar to within-plate granites. Thus, we consider that the alkaline plutons, in the eastern of Dong Ujimqi, had been formed in extensional tectonics, which indicate that ～272Ma maybe the tectonic evolution from Post-Orogenic to Anorogenic in Xing’anling-Mongolia Orogenic Belt.