In this study, the impact of sensitizer and activator ions concentration on the intensity of upconversion luminescence of nanoluminophores β-NaYF 4 :Yb 3+ /Tm 3+ in dimethyl sulfoxide (DMSO) was investigated. Analysis of all luminescence spectral bands allows one to establish that the ratio of concentrations of ytterbium and thulium ions strongly effects on the luminescent properties of nanoluminophores. Increase of sensitizer concentration at constant activator concentration leads to an increase of the luminescence integral intensity. Optimal concentration of activators at fixed sensitizer concentration was determined: 2 mol.% for thulium and 18 mol.% for ytterbium. The sensitivity of each luminescence spectrum band to changes in the concentration of activators and sensitizers was explained by cross-relaxation processes in activator ions. KEYWORDS up-conversion luminescence, nanoluminophores, rare earth elements, sensitizer, activator ACKNOWLEDGEMENTS This research was performed according to the Development Program of the Interdisciplinary Scientific and Educational School of Lomonosov Moscow State University "Photonic and Quantum technologies. Digital medicine". The study of the structure was carried out on the equipment of the Center Collective Use "Materials Science and Metallurgy" with the financial support of the Russian Federation represented by the Ministry of Education and Science (No. 075-15-2021-696).