Abstract: Waterborne sizing (DGEBA-MDI-TX100) of carbon fiber was designed and synthesized by using 4,4'-diphenylmethane diisocyanate (MDI) as chain extender and grafting the Triton X-100 (TX-100) on diglycidyl ether of bisphenol A (DGEBA). The carbon fiber surface was modified by the synthesized waterborne sizing, based on which carbon/epoxy composites were prepared by using epoxy resin as the matrix. The effects of waterborne sizing agent modified on carbon fiber surface properties and the interfacial properties of carbon fiber/epoxy resin composites were investigated. The results show that compared to the unmodified carbon fiber, wetting performance of carbon fiber has been greatly improved after modified by the sizing agents, the contact angle of modified carbon fiber and epoxy resin declined by 9.1%, and the interface shear strength of modified carbon fiber/epoxy resin composite material increases by 64.7%.