At present, the power grid contains a large number of multi-source information data, but due to the large size of the data types and high multi-dimensions, it is difficult to achieve effective data retrieval.According to the data structure of actual power operation system and multi-source database sample analysis, an improved decision tree algorithm based on mutual information is proposed as the kernel of data mining, and a parallel processing architecture suitable for power system is put forward, which can retrieve multi-source data fast and efficiently. The information is directly extracted from the original data of multi-source information according to the representative feature subset during searching. The index information is judged and sorted to form the decision tree model, and multi-source data is extracted simultaneously through Spark MapReduce Python data decomposition and parallel retrieval, so as to shorten the retrieval time. Taking a regional power grid database as an example to simulate and verify, the results show that the method can realize multi-source heterogeneous information extraction of power distribution network, effectively avoid duplicate data, and meet the requirements of online engineering decision.