Abstract: By the use of sessile drop and Wilhelmy plate，regularities of the total surface energy of two typical epoxy resin systems during curing were characterized；besides，polar and dispersive components of the total surface energy by sessile drop were well studied. The results indicate that the total surface energy in each resin system declines with the extension of time by the two test methods，and the surface energies obtained from sessile drop method is bigger in comparison with those from Wilhelmy plate method. The polar component of the total surface energy in the two resin systems declines with time elapse from the results of sessile drop. FTIR result shows that the change of polar component of the total surface energy in the epoxy 618-imidazole resin system is caused by the drop of content of hydroxyl and epoxy groups.