Abstract: Growth of large size fluoride crystals was based on the results of calculations and experimental research of thermal exchange in furnace heating units. Boundary conditions in containers of complicated configurations and two-dimensional task for temperature fields calculations in a growing crystal in different stages of technological process were solved. We presented here concrete data on temperature fields configurations and their transformation in process of crystal growth. All calculations were done using spectral and temperature dependence of optical characteristics of crystals, melt, container materials and also temperature dependence of their thermo-physical values.The results could be used in technological processes developments and in a design and construction of growth furnaces and containers. To this time these results contain the most precise data on temperature fields forming in fluorides crystal growth processes and systems.