This paper presents a dynamic model and simulation of the fuel delivery process between the separation system and the fueling system in the fusion fuel cycle considering the time-varying tokamak fuel demand. The fuel delivery process consists of vacuum pumps, valves, pressure vessels, and pipelines. Experimental data are applied to model the performance curves of the vacuum pumps. The delivery pressure is needed to be controlled to satisfy the pressure requirement of the fueling system. The developed dynamic model can be used to investigate delivery pressure fluctuation under various demand scenarios including a certain peak demand. The model is applied to the tritium delivery line during the inductive operation of the tokamak. Several rules for vessel switching are analyzed to examine the change of delivery pressure. The results show that the fluctuation can be reduced by switching vessels just before peak demand. The pressure fluctuation must be avoided by improving the flow coefficient of the control valve.