The relevance of the subject under study is to increase the yield of dry biomass of giant miscanthus plants by using fungi and bacteria in its cultivation technology. The purpose of this study was to determine the effect of mycorrhization of the root system of this crop by fungi and symbiosis with bacteria on the growth and development of plants and the formation of their productivity. Field studies were conducted at the Veselopodilska Experimental Breeding Station of the Institute of Bioenergy Crops and Sugar Beet of the National Academy of Agrarian Sciences of Ukraine (Poltava region) during 2017-2019 on saline and slightly saline black soil. The significance of the deviation between the experimental variants was determined by the P-level calculated according to the Student’s test. The use of symbiosis of fungi and bacteria with the root system of giant miscanthus contributed to positive results in improving plant growth, development and dry biomass yield. The use of biological products Mycofriend, Mikovital, and Florobacillin (fungi Glomus VS. and Trichoderma harzianum Rifa, Tuber melanosporum Vittad and bacteria Bacillus subtilis Cohn) significantly increased the area of the leaf apparatus (by 6.9-19.0%), the weight of the root system (by 4.1-16.3%), increased plant height (by 3.7-13.6%), and the number of stems (by 5.7-15.1%) compared to the control. At the same time, there was an improvement in the soil’s moisture-holding capacity by 10.3-23.7% and its structural and aggregate state – the proportion of clods 0.25-10.0 mm in size was 3.2-5.7% higher than in the control. The use of mycorrhizal fungi and nitrogen-fixing bacteria contributes to an increase in the yield of dry plant biomass by 1.82-6.11 t/ha compared to the control, which is of practical importance in increasing the raw materials for biofuel production