Abstract: The Bayan Obo deposit in China is endowed with the largest rare earth element resource in the world. The Wu dyke is one of the typical carbonatite dyke in the eastern part of the deposit, but its relevant age span is relatively large in previous studies. To solve the issue, we carried out a detailed petrographic analysis of section full scan, TIMA (TESCAN Intergrated Mineral Analyzer) scan, and trace element. The U-Pb dating was then carried out on zircons in the thin section of the quartz conglomerate that from the wall rock of the Wu carbonatite dyke. Petrographic analysis reveals three types of zircon distribution in the quartz conglomerate: most zircons are distributed in the contact area between quartz and orthoclase, and are accompanied by aegirine and albite in the surrounding areas; Some zircons are distributed in pure quartz, but some of them are surrounded by aegirine and albite particles; A small amount of zircon is distributed in orthoclase, and there are also amounts of albite and aegirine around zircon. The zircons in the quartz conglomerate have two main age peaks of ~2.5 Ga and~1.9 Ga, and secondary age peak of ~2.3 Ga. The minimum zircon age of 1844±18 Ma may represent the biggest sedimentary age of the Dulahala Formation in the Bayan Obo Group; all three types of zircons contain ages of 1.8~2.5 Ga. The Wu carbonatite dyke was formed at 1.4~1.3 Ga, and new zircons crystallized from the carbonatite magma when the dyke was emplaced, which is approximately coeval with the world-wide rifting events at this time that are associated with the final breakup of the Columbia supercontinent. Studies on the zircon ages of the Wu carbonatite dyke and wall rock show that the carbonatite dyke is contaminated with a large number of basement zircons. During the ~0.4 Ga period, the margins of some zircon in the Wu carbonatite dyke and in the Bayan Obo deposit were regrown, and some zircon cores were metasomatized. The ~0.2 Ga zircons from carbonatite that around the Bayan Obo deposit maybe formed by hydrothermal fluids and/or reactions involving zircon and dolomite during contact metamorphism resulting from hydrothermal input from emplacement of the Permian granitoids.