While petrologic characteristics and contact relations constitute the most direct and important evidence of the disintegration of granitic batholith, the accurate isotopic ages of the different series are important supplementary data. The Kulumusu granitic batholith is composed of Kulumusu and Shaque series. Detailed field investigation shows that the vein from Kulumusu series intruded into Shaque series. In addition, xenoliths of Shaque series are distributed in Kulumusu series. High-precision LA-ICP-MS zircon U-Pb dating of the Kulumusu series indicates that the weighted mean ²⁰⁶Pb/²³⁸U ages are 291.5±2.9 Ma and 290.9±2.9 Ma, and those of the Shaque series are 304.9±2.5 Ma and 304.1±2.9 Ma. The ages of the two series show that they were formed in different magma intrusion events, and the data obtained provide geochronological evidence for disintegration of the Kulumusu granitic batholith. The disintegration of the Kulumusu batholith not only provides new information on the geological features and facts of magmatic movements, but also is of significance and theoretical value in studying the tectonic evolution of this region.