In order to quickly and accurately gain the reactive power compensation scheme, evaluate the benefits of compensation scheme in low-voltage network more conveniently, and help power grid operator and manager to determine the most economical and suitable reactive power compensation scheme, a reactive power compensation and benefit evaluation system of low-voltage network is developed, which uses the Access relational database management system and Visual Basic 6.0 development tools. This system provides the intuitional and friendly interface, various power flow calculation methods and optimal reactive power compensation calculation methods of low-voltage distribution network, as well as the cost and benefit evaluation calculation of different reactive power compensation schemes. In addition, intuitionistic graphical interfaces is provided for grid operator inputting the information of new program low-voltage distribution network, and calculating the distributed reactive compensation optimal allocation scheme of the low-voltage distribution network. This system has been applied to practical low-voltage distribution networks in Nansha district of Guangzhou city, and it shows that this system is convenient to use and can reliably gain the practical distributed reactive compensation optimal allocation scheme of the low-voltage distribution network.