Abstract: To minimize the power losses in microgrids, we focused on the reactive power compensation by distributed generators connected to microgrid via electronic interfaces. Different from the existing distributed reactive power optimizations mainly for radial microgrids, we consider the reactive power optimization in a ring microgrid, which is implemented by locally distributed generations. Furthermore, we took into account not only the constraint of reactive power balance but also the bounded capacities of distributed generators. With a fully connected communication network, we propose a distributed algorithm for the reactive power optimization in a ring microgrid. Finally, we have verified the effectiveness of the proposed algorithm by undergoing several case-studies.