Main aim of this research was to investigate the overvoltage transients caused by the lightning strike to the transmission tower in an 110-kV AC overhead lines. Also design of grounding module is also discussed. The grounding system is an effective parameter on the magnitude of the lightning overvoltage of high voltage transmission lines At the place where the transition between overhead lines and substation is made, surge arresters were installed. Effect of surge arrester and proper selection and its characteristic were also studied. There are other factors which also need into taken into accounts transient overvoltage but for this research we are only focused on grounding module and Surge arrester. To observe and analyze the transients, different experiments were performed on a simulation software ATP-EMTP. Based on the results computer modeling, the transient characteristics of grounding devices and surge arrester were determined and the degree of influence of ground parameters on them was analyzed.