The acid / alkali pretreatment of windmill palm fiber (WPF) and the application of high voltage electrostatic force (HVEF) technology were used to prepare WPF-reinforced laminated veneer lumber (LVL). The effects of acid / alkali pretreatment on the surface morphology, chemical composition, crystallinity and mechanical properties of WPF were investigated. Moreover, the effects of intensity of HVEF on chemical composition and wettability of WPF were analyzed. Based on the mechanical experiment of WPF reinforced LVL composites, the mechanism of acid / alkali pretreatment and HVEF for the reinforcement of the composite was systematically clarified. The results showed alkali treatment efficiently removed silica particles and cuticles on the fiber surface and produced windmill palm fiber (ALWPF) with relatively high Young’s modulus and tensile strength (increased by 167.07% and 26.52%, respectively). After HVEF treatment, the increase of surface-active groups (- OH and - CHO) led to the increase of surface oxidation degree and water contact angle of WPF. Under the synergistic effect of acid / alkali pretreatment and HVEF, the interfacial properties between the adhesive and WPF were improved, which led to the effective improvement of the mechanical properties of WPF reinforced LVL. This study showed that the synergistic effect of acid / alkali pretreatment and HVEF not only broaden the application scope of WPF, but also provide insights into the engineering of LVL production.