In electric power systems, good electric power transmission is vital to occupy the load requirements. Power transmission capacity on transmission lines restricted by Surge Impedance Loading (SIL). When the transmission line loaded at its SIL value, then the transmission line will be purely resistive. If the transmission line is purely resistive, then the value of drop voltage will decrease and will improve the power quality. The voltage that below its reasonable value would cause the electrical equipment does not work in the maximum performance. When a transmission line SIL level is increased, the capacity of a transmission line will also increase. Increasing the level of SIL can be done by changing the configuration of the transmission line. The conversion is done inter alia, expand the diameter of the conductor, increasing the distance between sub-conductor, increasing the number of sub-conductor per phase, and decreasing the gap between phases. From all of these variations, it can be seen that the value of SIL and drop voltage of 500kV transmission line TASIK-DEPOK. From the results obtained, it can be concluded that the value of the largest SIL occurs when the number of sub-conductor as much as 6 pieces with the sub-conductor distance between 80cm. The highest SIL is 2429.45 MW, and the highest %voltage of DEPOK bus is 96.81%.