The article is devoted to issues of interaction rise in the system "polymer matrix - reinforcing filler," which provides an increase in the complex of composite properties. Both surface activation of the reinforcing filler and polymer matrix modification are considered as options. It has been demonstrated that the number of functional groups available for interaction at the surface of basalt fibers increases due to desizing and surface activation of the fibers, which provides an increase in the complex of basalt fiber reinforced polymer properties. It has been found that the use of different methods of surface activation allows providing high strength characteristics of carbon-, glass-, and basalt fiber reinforced polymers, exceeding similar characteristics of materials in which surface activation of the reinforcing filler was not performed. Experiments have proved that the use of unidirectional carbon fibers for reinforcement leads to a significant increase in the entire complex of mechanical properties, due to the possibility to realize stress-strain properties of the reinforcing filler to the limit.