© 2016 IEEE. this paper, is a study on the planning and development of the electricity distribution system to supporting economic and society growth in Luangprabang, from the year 2015 -2025, and to reliability improvement of the electricity distribution system in Luangprabang branch, based on the rate economic and social growth. This study also the examined the rate of return on investment (economic rate of return, EIRR and benefit cost ratio, B/C ratio). Reliability is assessing of the system after improvement of the electrical distribution system. Evaluating reliability will be considered explicitly to provide power to ensure stability and power to shrink. Therefore, improvement it should be considered terms of avoiding costs. These avoid costs, related to the reliability of an electric system index: Energy Not Supply (ENS), System Average Interruption Frequency Index (SAIFI) and System Average Interruption Duration Index (SAIDI) [12] .