With the ever increase in the demand of power, there is a need to transfer bulk energy from the generating end to transmission end y means of transmission line. As demand increases, there is a need for transmission of power in high voltage. Hence outdoor insulators play an important role. Insulators are subjected to corona over a long time in its lifespan sometimes even under clean condition.his may be due to lack of proper esign or due to faulty manufacturing.In this paper a comparative study of effect of corona has been made on newly emerging polymeric insulators and already existing porcelain insulators.

Keywords : Polymeric, Corona discharge, porcelain.