AbstractReducing basis weight could lead to huge savings of forest resources as well as energy consumption and waste treatment in the papermaking process. However, low basis weight paper generally lacks normal strength and stiffness. The lower the basis weight of the paper, the more important is surface sizing. Highly cross-linked cured epoxy resin, due to its epoxy group and phenyl group, has gained such outstanding mechanical properties and dimensional stability that it could be utilized to enhance paper strength and stiffness through surface sizing when incorporated with oxidized starch. In this study, the impacts of sizing volume, fluid temperature, curing agent, and curing system dosage on sizing were investigated. Our results indicated that a rigid resin layer and interpenetrating polymer network formed on the surface and in the inner layer of the paper, respectively. The formed resin layers strongly support the paper and thus resulted in the improvement of strength and stiffness.