The purpose. To study accumulation of 137Cs and 90Sr in biomass and lysimetric waters and to determine agroecological efficiency of elements of technique of growing Miscanthus large on the soils contaminated with radioactive substances. Methods. Lysimetric, biomorphological, radiometric, statistical, comparative-calculation. Results. Data on accumulation of radioisotopes in biomass of Miscanthus large and lysimetric waters are cited. It is established that the level of accumulation of radioactive nuclides in plants of Miscanthus on the low-purity soils depends on elements of technique of growing, radioisotope and its density in soil. It is established that in alternatives where biopower crop was cultivated on soils contaminated with radioactive nuclides, accumulation in biomass of 137Cs made 14,7–18,6, 90Sr — 0,46–0,54 Bq/kg, in lysimetric waters — 4,36–4,57 and 0,28–0,65 Bq/l accordingly. Importation of fertilizers together with defecate and treatment of Miscanthus rhizomes before planting with microbial preparation Polimiksobakterin together with BioMAG promoted 28% increase of yield of dry biomass as compared to control. Conclusions. Application of fertilizers in a complex with chalking, inoculation of Miscanthus rhizomes with microbial preparation Polimiksobakterin and pre-sowing treatment with organomineral fertilizer BioMAG promoted essential increase of yield of dry biomass, decrease of 137Cs and 90Sr in biomass and lysimetric waters. Accumulation of these radioisotopes in Miscanthus biomass at growing on soils contaminated by radioactive nuclides did not exceed allowable level, and application of elements of technique promoted lowering content of 137Cs on 12–21%, 90Sr — on 9–15% as compared to control alternatives. At use of fertilizer complex «mineral fertilizer + defecate + Polimiksobakterin + BioMAG» they gained the least accumulation coefficients in Miscanthus biomass (137Cs — 0,07, 90Sr — 0,05), and in lysimetric waters (137Cs — 0,02, 90Sr — 0,03 ).