The performance of Earthing grid system is very important to ensure the human and protective devices in safe environment. Actual Step and Mesh voltage of a substation must keep under the maximum allowable limits under fault condition. Ground potential rise, GPR is greatly influence on actual step and mesh voltage of substation grounding system. Ground potential rise also mainly depends on the length and numbers of ground rods and grid spacing. This paper presents performance analysis of actual step and mesh voltages of a substation grounding system under the variance of length and number of ground rods. The performance result is also carried out by using current injection method and with the help of MULTISIM simulation software.