Abstract: Glass fiber reinforced polymer (GFRP) composites are widely used in the fields of wind turbine blades and sports equipment due to their low cost, excellent mechanical performance and fatigue resistance. However, poor compatibility between sizing agent and resin can easily lead to interlaminar delamination. In this paper, the mode I interlaminar fracture toughness of GFRP with bisphenol F and bisphenol A epoxy resin matrices is improved by 71.7% and 23.4% through spraying a carbon nanotube (CNT) spray layer on the surface of fiberglass fabrics without sacrificing in-plane properties. Experimental results show that the CNT/acetone dispersion spray process stably loads CNTs on fiberglass and successfully changes the surface morphology of fiberglass. Through mechanisms such as mechanical interlocking, pull-out energy consumption, extension of crack propagation path as well as triggering of fiber bridging, the GFRP with different resin matrices is successfully toughened.