Three dimensional solid-fluid interaction numerical analysis models of both the finger seal with herringbone-grooved pad and the finger seal with herringbone-grooved rotor were established in order to study the performance of hydrodynamic finger seal. The models investigated fluid radial under pad force and fluid leakage as a function of both the rotor speed and the high- to low-pressure differential. It was shown that the finger seal with herringbone-grooved structure in pad or in rotor could bring lift force under the finger pad so as to keep the finger seal in non-contacting status. For the two types of finger seal, their load carrying ability and fluid leakage varying with the pressure differential were almost same. In the same velocity of rotor surface, the load carrying capacity of the finger seal with herringbone- grooved rotor was greater and the leakage was less than that of the finger seal with herringbone-grooved pad respectively. With the conditions of rotor structure allowing, it is suggested to select the finger seal with herringbone-grooved rotor first for designing the hydrodynamic finger seal with herringbone-grooved structure.