The security and stability control system of the smart grid is the "second line of defense" of the power system. The defect anomaly analysis of its stability control device is the basis to ensure the stable operation of the power grid. This paper proposes a correlation analysis method for smart grid safety and stability control device defect based on improved Apriori algorithm. Firstly, we collect the defect data of the stability control device, and the improved Apriori algorithm is imported after coding qualification. By calculating the support degree and confidence degree, the defect characteristics and influencing factors of the stability control device and the mapping relationship between the modules are analyzed. Secondly, the proposed method can effectively realize the correlation analysis and traceability of the defects of the stability control device, which provides a theoretical basis for preventive maintenance and fault maintenance of operation and maintenance personnel, and the improved Apriori algorithm also reduces the time complexity and saves the memory space. Finally, the effectiveness of the proposed method is verified by a simulation example of actual smart grid safety and stability control device defect data.