Abstract: Several ultra-high earth and rockfill dams up to 250 to 300 m in height are to be built in the intensive earthquake regions of West China. The strong outburst and high uncertainty of strong earthquakes pose a great threat to the safety of ultra-high earth and rockfill dams. The seismic safety evaluation of the ultra-high earth and rockfill dams is a multi-system, three-dimensional, nonlinear and discontinuous problem. However, the traditional dynamic analysis of high earth and rockfill dams is still within the range of weak nonlinearity, and the effects of multi-system interaction are mostly simplified and carried out in isolation, which is difficult to reveal the dynamic failure process and coupling effects of the ultra-high earth and rockfill dams under strong earthquakes. The project is oriented to the construction needs of 300 m-ultra-high earth and rockfill dams. Relying on the ultra-high earth and rockfill dams such as Lava and RM, the strong nonlinearity of the rockfill materials, dam-foundation-reservoir interactions, refined modelling methods, high-performance software and the assessment methods and criteria for the ultimate seismic capacity of the ultra-high earth and rockfill dams are studied. The results can provide advanced assessment methods and criteria for the aseismic design of ultra-high earth and rockfill dams.