In the seismic PSA project, the seismic failure correlation analysis of redundant equipment has a great influence on the quantitative results of the whole PSA, which is also a difficult problem in the seismic PSA technology. Different from the failure correlation analysis of other equipment, the data of CCF of nuclear power equipment under earthquake are very limited, so it is difficult to calculate the failure correlation coefficient of CCF by empirical formula. The traditional seismic failure correlation analysis method, which is either 1 or 0, is too conservative for the redundant equipment of the same system. Therefore, it cannot reasonably evaluate the effect of the redundant design of the power plant safety system under the earthquake. Therefore, for the equipment with dominant cut concentration of seismic PSA results, it is necessary to carry out the mechanical Rationality Research of equipment failure correlation analysis under earthquake according to different scenarios. In this project, a system failure probability model that reflects failure correlation is established based on the generalized stress intensity interference analysis of the system layer. Additionally, the seismic PSA quantitative integral calculation is transformed into a discrete polynomial summation form using integral model discretization technology. At the same time, the principle of total probability calculation is applied to reflect the weight effect of multiple seismic risk curves. Through the influence of the number of discrete intervals in the seismic range on the stability of the calculation of the failure correlation coefficient, the recommended number of discrete intervals in the seismic range in the quantitative calculation is given. Finally, based on the seismic risk data and seismic vulnerability parameters, a method for accurately calculating the probability of multiple basic earthquake failure events (including all stages of failure) in the same cut set is established ∝ Based on the concept of factor model, the calculation method of system failure correlation coefficient under earthquake action is given. Based on the above work, a set of calculation program for failure correlation coefficient of nuclear power equipment is designed and compiled. Taking the typical system of nuclear power plant as an example, the calculation of failure correlation coefficient is carried out. The research results of this project can solve the problem of correlation analysis of equipment failure under earthquake in the industry and promote the development of seismic PSA technology in China.