In addition to addressing the challenge of investigating the flammability and mechanical properties of polymers, this study not only unveils the potential of maleated epoxy resin/epoxidized corn oil thermoset blend, which provides a solution for in-situ processing of vinyl ester polymer networks, but it also utilizes the unique crosslinking effect of epoxidized corn oil into thermoset polymers to improve the significant properties. Thus, an efficient and environment friendly flame-retardant MEPECO added to vinyl ester resin were synthesized, optimized, and characterized.