In view of the characteristics of shale gas plugging in Sichuan and Chongqing block，such as high pressure and easy backflow，the anti-backflow plugging agent（ARP）was developed with high softening point resin as the main body. The dispersion of ARP plugging agent in the field oil-based drilling fluid and the bonding strength with the field plugging agent were evaluated in the laboratory. Its pressure-bearing capacity and anti-backflow capacity after cementing and solidification were tested. The results showed that the best formula of ARP plugging agent was obtained as follows：epoxy resin（softening point 90 ℃），iron ore powder，20% diethyl toluene diamine. When the density of the plugging agent was 1.8 g/cm³ and the particle size was 0.5—2.0mm，it had good dispersion in the field oil-based drilling fluid. ARP plugging agent had the ability of deformation，cementation and solidification. When ARP plugging agent was used in combination with bridge plugging particle，it could cement and solidify with other ordinary plugging particles in formation fractures，thus improving the pressure bearing capacity and anti-backflow ability of the overall plugging slug. When ARP plugging agent was combined with field plugging agent，the appropriate proportion of ARP was 15%—25%. Meanwhile，the cementing strength of the composite plugging agent could reach 2.7—7.8 MPa. When the lost circulation slurry prepared by ARP was used to seal fractures with 2—3 mm width，the positive pressure bearing capacity could reach 8 MPa，while the anti-backflow pressure bearing capacity could reach 3.3 MPa. According to the characteristics of materials， the site construction technology was designed and applied in a well in Changning，Sichuan. A good plugging effect was achieved.