Abstract: The exposure to electric field now-a-days is an integral part in the design area of electrical power apparatus and systems. Moreover, the electric field produced by power lines, busbars and all high voltage equipments inside High Voltage (HV) substations is receiving more and more concerns to guarantee the life insurance of workers inside these substations. Therefore, the possible effect of the electric field exposure raises the question of how electric fields are created and what effects they may have. Therefore, monitoring the electric field inside Air Insulated Substation (AIS) and Gas Insulated Substation (GIS) is achieved in this study. This study not only depict the electric field distribution inside AIS using Charge Simulation Method (CSM) in three Dimensional (3D) and many Matlab M-files modeling programs developed by the researchers but also measured it inside AIS under 500 and 220 kV busbars and inside GIS nearby the 500, 220 and 66 kV busbars. The simulation results of AIS are compared with the measured values and the simulation results are matched with the measured values with very small tolerance about 1.4% for 220 kV model and about 4.4% for 500 kV model.