Abstract: The present invention relates to the technical field of composite materials, and in particular to a fiber composite material and a preparation method thereof. The preparation method comprises: A) uniformly dispersing nanoparticles in a solvent to obtain a nanoparticle dispersion; B) uniformly spray-coating the nanoparticle dispersion on a chopped fiber nonwoven fabric, and drying the fabric to obtain a nano-modified chopped fiber nonwoven fabric; C) intercalating the nano-modified chopped fiber nonwoven fabric between fiber preforms, and subjecting the obtained material and a resin matrix to composite molding by a molding process to obtain a fiber composite material. In the present invention, firstly nanoparticles are uniformly dispersed in a solvent to obtain a nanoparticle dispersion; secondly, the chopped fiber and the nanoparticles cooperate to construct a multi-scale interlaminar toughening phase, which significantly improves the interlaminar fracture toughness of the fiber composite material.