The influence of the structure and position of groove in a two-dimensional metallic subwavelength slit on transmission properties has been studied with the finite-difference time-domain method. The whole structure of slit with perpendicular groove could be regard as a LC oscillation circuit. The capacitance and inductance of this oscillation circuit will be altered when the structure of groove varies，so that the resonant transmission peaks shift. And the drive source of circuit changes when the position of groove moves along the slit, as a result the distribution of electromagnetic filed in the structure is changed also. So the resonant transmission peaks are split. In this paper， the change of resonant transmission peaks as each parameter of the groove changes is analyzed with the principle of LC resonance.