Abstract: Probabilistic safety assessment (PSA) is one of the two major safety analysis methods in the field of nuclear energy safety analysis. Starting from the concept of PSA, this paper firstly compares the difference between deterministic safety assessment and probabilistic safety assessment from the theoretical basis and analytical perspective. Secondly, it combs the historical process of PSA in the field of nuclear energy safety analysis, and through reviewing the changes in technology and regulations of PSA, it shows the mutual promotion relationship between PSA and nuclear energy safety in the process of upgrading. Thirdly, the application of the PSA method in risk quantitative prediction, balance safety design, risk safety-making, and risk safety supervision is expounded, and the application of PSA in nuclear energy safety assessment is illustrated by HPR1000. Finally, the future development direction of PSA technology is predicted. It points out that the deterministic safety assessment and probabilistic safety assessment will deeply integrate, and the PSA analysis will shifts from security target to task target, from static to dynamic, and from cognitive to perceptual direction.