Abstract: Based on the total design requests of carbon fiber reinforced composites, the properties of strength of the epoxy resin matrix available for wet fiber wilding compo-sites and its study methods were described in this paper. The text introduces a new middletemperature cured epoxy resin system such as SY-6# which is used in the fiber wilding process with T700 carbon fiber, and puts the emphasis on the study of rheological behaviors and curing process by testing mechanical properties, viscosity, thermal properties measured by the differential scanning calorimeter (DSC) and curing degree tested by IR.