Abstract: A lumped parameter model was proposed to research dynamic performances of plate-fin recuperator in hightemperature gas-cooled reactor with direct helium turbine cycle(HTGR-GT). The model with infinite core heat capacitance could be numerically solved by fourthorder Rounge-Kutta method. Based on this lumped parameter model, transient responses of outlet temperature of recuperator were analyzed when step and ramp changed of inlet temperatures and mass flow rate took place in hot side. Moreover, transient responses of outlet temperature and core temperature were analyzed while power of HTGR-GT was regulated in normal operation condition and total electric load was rejected from full power. The model can be applied to analyze dynamic performances of plate-fin recuperator.