Objectives: The paper has discussed the formation environment and recharge source of geothermal water, based on the analysis of hydrogeochemical and geological conditions in the Mianhuakeng Uranium Deposit, Northern Guangdong. Methods: This paper was based on the methods of hydrochemical analysis, H—O isotope analysis and comprehensive study of water samples. Results: The geothermal water type was HCO3-—Ca2+—Na+, and δDV-SMOW ranged -44.5‰~-40.7‰, δ18OV-SMOW ranged -6.8‰~-6.4‰, distributed near the local rainwater line which was caused by atmospheric precipitation. The water had strong renewability, short runoff distance and weak water—rock effect, which thermal storage temperature was 67.8℃, recharge source altitude 650~1150 m, circulation depth altitude -1250~-660 m, and d- excess value ranged 7.5‰~10.5‰ The uranium content which was 40~120μg/L indicated that the geothermal water was formed in an oxidizing environment. Conclusions: The recharge source was come from Nanshan area which was located in southeast of the deposit, according to the geological and geomorphologic characteristics of granite area in northern Guangdong. The groundwater depth recycle was the main reason of geothermal formation. To some extent, the present geothermal water activity has inherited the characteristics of the paleo hot water during the metallogenic period, which had a promoting effect on the formation of uranium deposit. The depth recycle of the geothermal water has indicated that there was a very good prospecting potential in the depth of the deposit.