In this study, hydrothermal carbon doped with phosphorus using phytic acid (PA) and Sodium tripolyphosphate as functional monomers was successfully synthesized by the hydrothermal route combined with microwave-assisted hydrothermal carbon as matrix material. The uranium(VI) adsorption capacity by phytic acid functionalized microwave-assisted hydrothermal carbon (MHC-PA) was up to 382.2 mg/g at pH of 6.0 and the temperature of 298.15 K. The adsorption mechanism of uranium(VI) onto the MHC-PA was mainly the chelation of P=O, P–OH functional group and uranium(VI), which improves the selective adsorption performance of MHC-PA for uranium(VI).