The individual or joint effects of annealing and equal channel angular pressing (ECAP) treatments on the high-temperature compressive deformation and damage behavior of cast LY12 Al alloys were studied. The compressive deformation behavior and surface deformation and damage characteristics of differently treated LY12 Al alloy samples were examined at temperatures ranging from 25°C to 400°C. It is found that the LY12 Al alloy exhibits different compressive mechanical behavior depending on different treatments, and the compressive deformation and damage characteristics of LY12 Al alloys with different microstructural states are closely related with the testing temperature. As compared to other samples (e.g. as-cast, annealed, as-cast+2ECAPed), the sample annealed at 450°C for 3h followed by ECAPed for 2 passages (i.e. annealed+2ECAPed) shows a better high-temperature deformation stability.