In order to obtain a suitable high strength plugging agent for tight fractured reservoirs treatment，epoxy resin was investigated in this work. The effects of the diluent on the dilution，ageing time，density，strength and contractility of epoxy resin were studied. The results showed that the absolute ethyl alcohol had a good effect on the dilution，and it also had little effect on the epoxy resin strength. But the excess ethyl alcohol would lead to a high contractility. The diisobutyl phthalate（DBP）was used to combine with ethyl alcohol，and it showed a good performance when the mixed proportion was in range of 1∶3—1∶5，and the setting time was controllable. The addition of the silica fume could significantly improve the setting strength up to 10 MPa，and the contractility was only about 1%—2%，meanwhile，the cured product of the resin plugging agent had certain toughness. Besides， the density of the plugging agent should be adjusted close with the formation water. The plugging ratio could be more than 99%， indicating that the system was suitable to seal large cracks.