Abstract: Substation is of great significance to ensure the safe and stable operation of power system. Considering the complex operation state of equipment at the primary side of intelligent substation, which is difficult to carry out intelligent integral evaluation, and the large consumption of computing resources of common state evaluation algorithms, this paper studies and proposes a method for monitoring the operation state of equipment in intelligent substation based on random forest. The structure of intelligent substation equipment operation state monitoring system is designed, and the operation state detection principle of the primary side equipment in intelligent substation is described. On the basis of the equipment operation data, a state evaluation method based on random forest is proposed for real-time evaluation of intelligent substation equipment operation. The effectiveness of the proposed method is verified by experimental analysis.