In this paper, through field investigation, petrography analyses of samples of the bojites, 1 sample zircon LA-MC-ICP-MS U-Pb dating and 10 samples geochemical analyses, bojiteson in the southeast margin of Siberian plate have been studied, for their chronology and tectonic implications. In these rocks, main rock forming minerals are plagioclase, hornblende and clinopyroxene. The zircon U-Pb dating suggest that these bojites are formed in Early Permian with detail ages of (280.8±1.5) Ma.Geochemical researches indicate that the bojites are high in silica (SiO2＝48.87%～53.70%), TiO2 (0.73%～2.27%), Al2O3 (15.05%～16.69%), moderate to high MgO (4.84%～9.25%), FeOT(6.91%～10.47%) and low CaO (5.80%～7.94%). These rocks are enriched in Na2O (2.75%～3.90%), especially LILE (Ba, Sr, K), and depleted in K2O (1.01%～1.90%) and HFSE (Nb, Ta, Th), with the characteristics of alkaline and tholeiitic series. The rocks have high REE (97.50×10-6～251.16×10-6) , slightly Eu anomalies (δEu＝0.85～0.98), enrichment in LREE and relatively depletion in HREE\[(La/Yb)N＝4.23～7.12\], with the high Zr(87×10-6～289×10-6) and Zr/Y (4.03～7.66), which is similar to within-plate rocks from mantle magmatism. Thus, we consider that the bojites, in the southeast of Siberian plate, had been formed in extensional tectonics from partial melting of the Enrichment Mantle peridotite, with fractional crystallization, which indicates that ～280Ma may be the tectonic evolution from Post-Orogenic to Anorogenic in southeast margin of the Siberian plate.