Abstract: The accident sequence precursor analysis method was adopted to evaluate qualitatively and quantitatively the licensee operation events of units 1 and 2 of a nuclear power plant, and the potential accident sequence precursors or general accident sequence precursors were identified, which were some risk significant events and were important for experience feedback.By the statistics, classification and trend analysis, the results showed that the causes of the potential accident sequence precursors or general accident sequence precursors of units 1 and 2 of a nuclear power plant were defects or failures of the equipment.Therefore, the most effective measure to reduce the number of the potential accident sequence precursors or general accident sequence precursors is to improve equipment performance, especially the equipment performance of the systems of control rod and the power transmission and transformation.This article provides effective supports for improving the nuclear safety management level of a nuclear power plant.