Epoxy resin is a thermoplastic resin. It can show excellent performance only with adding curing agent to form three-dimensional network structure by cross-linking reaction. Therefore, the selection and combination of curing agent is the key factors to determine the performance of epoxy resin. 4,4'-diaminodiphenyl sulfone (DDS) is a widely used high-temperature curing agent, but it has some shortcomings, such as high viscosity mixed with epoxy resin and high reaction temperature. In this paper, 3,3'-diethyl-4,4'-diaminodiphenylmethane(DEDDM), 4,4'-diaminodiphenylmethane (DDM), 4-methyl-1, 3-cyclohexanediamine(HTDA) were used to combined with DDS. Non-isothermal DSC method was used to study the reaction activation energy of different contents and kinds of the mixed curing agent. The effects of the contents and kinds of the mixed curing agents on the thermal properties of the cured product were studied by DMA and TGA tests. The results showed that when the content of DDM was 20% (mol ratio), the viscosity decreased by 70.4% at 80℃, the average reaction activation energy decreased by 2.99kJ/mol, and the glass transition temperature remained 219℃, which met the requirements of high temperature resistant resin. Considering all aspects of properties, the system 20DDM can be used as the first choice of mixed curing agents for epoxy resin composites.