ABSTRACT Epoxy resin is widely used in fiber‐reinforced composite structures, but its application in high‐end projects is limited due to the relatively brittle characteristics caused by its high crosslink density. In this paper, the reaction process of ZnO surface treated with silane coupling agent is described, and the toughening mechanism of nano‐ZnO on resin matrix is elaborated. A three‐level three‐factor experimental strategy has been designed, and orthogonal experimental tests were conducted to investigate the influence of different design parameters, such as solid–liquid epoxy resin ratio (SLR), mass contents of nano‐ZnO and catalytic agent (2E4MI). With the results of three‐point bending (3P‐bending) tests and hardness tests of the beams prepared with twill woven fabrics, surface response analysis based on statistics was carried out to evaluate and optimize design parameters. Results show that, for the beam with the optimized configuration, the maximum bending load, bending stiffness, and hardness were increased by 40.02%, 51.25%, and 58.18%, respectively.