Distribution power network is an important part of the grid, which can effectively ensure the power supplying and applying. It is the key to directly facing to power users. At present, in the field of distribution network planning, planners carry out the relevant analysis mainly relying on artificial mode and experience, not yet mastering the necessary calculation and analysis methods, and the lack of appropriate quantitative analytical tools for support. The current situation can not meet the managerial requirements of intensification and leaning. Therefore, it is an inevitable development tendency to study on calculation and analysis met hods of distribution network planning, then apply the computer technology and develop calculation&analysis software combining with the practical experience of planners. These ways can finish the quantitative analysis to different distribution network planning schemes. This article study some calculation&analysis methods in distribution network, which include the topics of the distribution power flow, short circuit current, security of supply, reliability and distribution network assessment. A distribution network calculation & analysis software is developed based on power supply reliability. The software can achieve quantitative analysis of different distribution network planning solutions, which can effectively improve the level of scientific planning in the distribution network.