Abstract: The aging process of isothermal transformation and eutectoid transformation were studied by using DSC and high temperature microscopy.Compared with conventional methods,DSC has the advantages of rapidity,accuracy,simpler specimen preparation and convenient operation process.In addition the speed of eutectoid transformation in heating ZA27 alloy is very fast and the eutectoid transformation originated at the grain boundary firstly,then spread rapidly into grain interior as the temperature increased.