Abstract: In order to explore the geomorphological evolution and climatic environment changes in the chemical weathering process of the granites in northern Guangdong, Jinjiang River Basin is selected as the research area and the uranium-series isotopes disequilibrium method is used to measure the uranium concentration and ²³⁴U/²³⁸U activity ratios of river water, weathering crust and rock in the basin and calculate of chemical weathering rate of grani-te in the basin. As the results show, under the current climatic conditions, the chemical weathering rate of the grani-te weathering crust with the CIA of 86.84 is 0.038 mm/year, which means that it will take about 26 000 years for 1 m thick granite to weather; in the tropical and subtropical regions, and the main factor for rock weathering is the climate conditions with high temperature and humidity. Uranium isotopes disequilibrium can be used to quantitatively evaluate the interaction among water, soil and rock under weathering, and it also provides a new means for research on rock weathering and earth surface processes.