Method for producing a nanocomposite material reinforced by unidirectionally oriented pre-dispersed alumina nanofibers. The process is suited for industrial-scale production of the nanocomposite materials. The nanocomposite production process involves, synthesis of unidirectionally oriented pre-dispersed alumina nanofibers, casting a mat of pre-dispersed nanofibers with a predetermined orientation in the atmosphere of air or other gas(es) by saturating the nanofibers with liquid polymer matrix. Polymer matrix may include thermosets or/and thermoplastics. The material forming the polymer matrix may be heated to its melting point temperature to transform it to liquid phase. After saturation, the polymer matrix is hardened by lowering its temperature or by means of exposing the polymer matrix to UV radiation, electron beam and/or chemical hardeners. The nanomaterial is composed of polymer composite with homogeneously dispersed uniformly oriented reinforcing nanofibers. Subsequently, the nanofibers in the nanocomposite are dispersed by means of subjecting to hydrodynamic stress, mechanical or/and ultrasound coarse dispersing.