The influence on the strength of cement mortars by adding emulsified epoxy is studied, and epoxy resin polymer cement mortars with excellent performances are made up through modifying ordinary Portland cement with emulsified epoxy and micro-fine slag. The microstructure of the epoxy resin polymer cement materials are studied and their action and mechanism are discussed by means of modern detection measures such as SEM, XRD. The experimental results indicate cement mortars modifying emulsified epoxy and micro-fine slag have higher compressive strength and flexible strength. The series effects of water-reducing, density, pozzolanicity, filling and solidification cross linking through the action together of epoxy organism and micro-fine slag can endow cement-based materials with perfect mechanic performance. The main hydration products in the system are C-S-H gel and micro-crystal hydrated calcium aluminate. When epoxy resin is solidified, the organism is network. No Ca(OH) 2 has been found.