Acycloaliphatic(CDR-0122) epoxy resin has good heat-resistance, but it is characterized by being brittle. CDR-0122 modified with different mass fraction of epoxy (E-51) were studied. First, DSC analysis was carried out to determine the activation energy, reaction order and the best curing procedure of the modified resin. Then mechanical property and heat-resistance property of the cured modified resin were tested. The results showed that, compared with the unmodified CDR-0122, the activation energy of the modified resin system decreased slightly, and its tensile strength and flexural strength increased by 52.38% and 54.77%, respectively, but the glass transition temperature decreased slightly. Considering all aspects of performance, the system of CDR-0122 modified with 30 wt% E-51 is the best one.