Abstract: The safety and reliability of digital reactor protection system software need to be focused. In the verification and validation (V&V) process of each stage of software life cycle of protection system, it is of great significance to carry out hazard analysis on software to check, analyze and determine the possible hazards of software, the accidents caused by hazards, the possible impacts and safety control measures. Generally, technologies such as preliminary hazard analysis table, preliminary hazard analysis, event tree analysis, failure mode and effect analysis, fault tree analysis and probabilistic risk assessment were adopted. Combined with the practice of digital protection system in an experimental reactor project, the application methods of these hazard analysis technologies were explained. The results show that the comprehensive use of hazard analysis technology can effectively alleviate or prevent the risk of system hazards caused by software and the software safety of protection system is improved.