Abstract: The performance-based seismic fragility analysis can effectively estimate structural damage under earthquake action and become one of the important methods for seismic safety assessment. The maximum settlement and the horizontal maximum displacement of the dam crest are taken as the performance parameters. It is proposed to consider the seismic situation of the dam site to determine the number of input ground motions. The performance levels are determined based on the catastrophe point of the performance parameters. Firstly, the ground motion of Nuozhadu earth-rockfill dam site is reasonably determined to be suitable for the ground motion of the high earth-rockfill dam, and the dynamic analysis is carried out by using the improved PZC elastoplastic constitutive model and the dynamic consolidation finite element program SWANDYNE II. By regarding the maximum settlement and the horizontal maximum displacement of the crest as the performance parameters, the performance level of the high earth-rockfill dam is determined through the dynamic analysis of 60 selected ground motions. The elastoplastic model-nonlinear method is used for dynamic analysis, and the MSA method is used to obtain the seismic fragility curve of the performance parameters. By analyzing the relationship between the variation coefficients of the average and standard deviations of performance parameters and the number of ground motions, it is determined that the variation coefficients of the average and standard deviations of performance parameters almost do not fluctuate when the number of ground motions exceeds 30. Finally, the seismic safety of Nuozhadu high earth-rockfill dam is determined by the results of seismic fragility and the seismic risk curve. The results may provide a basis for the researches on the seismic performance of high earth-rockfill dams.