South Sumatra kelampung requires a 150 kV transmission line which is relatively very far away and prone to conductor disturbances. In addition, with the high demand for electrical energy, the average transfer value is close to the maximum value so that when a disturbance occurs on the transmission line it will have an impact on a very large deficit blackout. The method used is by collecting power flow data, system loading and transmission line models, then modeling the current distribution system conditions and making comparisons after planning the new transmission line system to maintain the reliability level of the Lampung electrical system. From the research results, the construction of KayuAgung - Gumawang transmission is analternative solution to overcome the problem of high energy transfer requirements and currently only supplied through one transmission line location. The addition of the KayuAgung-Gumawang ransmission line will increase the maximum transfer capacity to 760 MW, so that the reliability of the Lampung system will be maintained with the value of the power reserve that meets the N-1power plant in the Lampung system, which is 80 MW.