To prepare a high-performance epoxy, we synthesized three types of diamines {N,N ' -(4,4 ' -diphenylether)-bis (4-aminophthalimide), 4,4 ' -bis(p-aminophenoxy)dibenzalphentaerythriol, and 2,2 ' -bis[4-(p-aminobenzoyl)phenyl]propane} as epoxy curing agents with a two-step reaction sequence. The structures of the synthesized diamines were confirmed with Fourier transform infrared and nuclear magnetic resonance spectroscopy. The curing kinetics and thermal stability of the cured epoxy resin with diglycidylether of bisphenol A were estimated with differential scanning calorimetry and thermogravimetric analysis under a nitrogen atmosphere. The kinetics parameters were determined with the Ozawa and Kissinger equations.