It is not uncommon for nuclear power plant systems, equipment or components to malfunction. If such malfunctions are not handled promptly and properly, they may escalate into accidents. Therefore, it is crucial for nuclear power plants to establish a comprehensive accident operational procedure system. The second-generation nuclear reactors mainly adopted two sets of accident operational procedures: state-based accident operational procedure, commonly referred to as SOP, and symptom-based accident operational procedure, commonly referred to as EOP. As a third-generation nuclear power technology developed by China, the Hualong One reactor adopts the SEOP operational procedure system, which combines the advantages of the SOP and EOP systems and provides an innovative approach to accident handling. However, in practical applications of nuclear power plants, the SEOP operational procedure system has also exposed several shortcomings and limitations. This paper mainly compares the differences and advantages and disadvantages of the three accident operational procedure systems (SOP, EOP, SEOP) and proposes several improvement measures for the SEOP operational procedure system based on the E01 and E02 procedures (primary coolant circuit loss of water accident), effectively improving the efficiency of accident handling.