The construction of a new distribution network with new energy as the main body is not only an important direction for the transformation and upgrading of China’s power system, but also a key way to achieve the goal of carbon peak and carbon neutralization. Using scientific and reasonable methods to evaluate and analyze the operation situation of the new distribution network is helpful to find its weak links and provide corresponding guidance and basis for its construction and operation. Aiming at the new distribution network, a new distribution network operation situation assessment method based on big data mining is proposed. The sample data is cleaned by big data preprocessing technology, and a new distribution network big data mining and feature extraction method based on K-means clustering algorithm is proposed. The new distribution network evaluation index system is constructed, and the subjective and objective combination weighting method is used to assign weights to the indicators. The comprehensive evaluation method of cloud model is proposed, and the quantitative evaluation and grade division are realized by using the evaluation grade standard cloud. The results show that the proposed method can excavate the weak links of the new distribution network and provide data support.