Effects of contents of curing agent on thermal properties of DGEBA/MDA/SN system were investigated by dynamic DSC analysis. Both of activation energy and pre-exponential factor decreased, and reaction rate constant increased with increment of MDA contents. Glass transition temperature(T_g) increased with increase of post-curing time(0,3,6 and 20 hr) in DGEBA/MDA/SN system and increased with increase of MDA contents(23, 26 and 30 phr). This may be the result of the increase of the cross-link density with the increment of MDA contents.