To solve the problems of dynamic state evaluation of large-scale distribution equipment and complex and changeable smart grid, and realize efficient planning, operation and maintenance. Based on the existing literature, this paper explores the distribution network health index theory and distribution network operation and maintenance strategy. The distribution network planning method based on health index is studied. Based on the existing power system research indexes, the suitable intelligent grid evaluation indexes are selected from the aspects of safety, economy, reliability and environmental protection, and an index system for comprehensive evaluation of smart distribution network health is selected. The critical characteristics of distribution network are classified, the indexes are established and the distribution network health grades are divided by analytic hierarchy process and entropy weight method. In this paper, the evaluation method is used to calculate the health index, classify the health degree and generate the health degree image for seven lines in a 110kv substation in oil field. According to the optimal operation and maintenance strategy of distribution network based on health index theory, it provides a reliable basis for distribution network planning, construction, operation and maintenance.