Literature review summarizes the information about plant fiber and polymer composites, composite matrices, reinforcing components, their properties and applications. Increased attention has been paid to the properties of hemp fiber reinforced composites, methods of obtaining, modification of reinforcing components and adjustment of parameters. The methodological part includes the used methods in research process - technologies and testing methods, equipment, production processes and regimes, applied research methods and determinable parameters. The experimental part of the work describes the reinforcing components of the hempbased composites, the effect of mechanical and chemical modifications on the properties and sizes, the quality of coatings and the most appropriate combination of sols. The mechanical, physical and operational properties of the composites obtained, the optimal working parameters, the percentage of reinforcing components and additives, time modes have been analyzed. The results of the research have resulted in composites with a high content of reinforcing components, which maintains the ability to flow in a viscous state, improved mechanical properties and low water absorption. The doctoral thesis is written in Latvian; consist of an introduction and 3 main chapters: review of the literature, methodological part, experimental part and conclusions. The amount of work contains 121 figures, 29 tables, 23 equations, together 163 pages; 189 references used in the work.