Neutral point grounding mode has a decisive influence on the reliability of distribution network power supply. However, the study of the influence of the traditional neutral point grounding mode on the reliability of the power grid is based on the indexes such as the number of blackouts and the time of power failure, which lacks the consideration of the topology of the distribution network. Based on the shortest path statistical characteristics in complex network theory, this paper analyzes the influence of the neutral point grounding mode on the branch impedance and the load distribution of the distribution network, and the reliability evaluation system of distribution network is constructed. On the basis of this system, the reliability of the neutral point grounding mode is obtained by using the field data, which provides an effective reference for the selection and optimization of the neutral point grounding mode.