Phase equilibria in the SrO-Bi2O3-B2O3 system have been investigated by X-ray powder diffraction analysis and DTA. Ternary compounds SrBiBO4 and Sr7Bi8B18O46 congruently melting at 820 ± 5°C and 760 ± 5°C have been found. Quasi-binary sections are determined and the isothermal section of the system in the region Bi2O3-Sr2Bi2O6-Sr3B2O6-B2O3 at 600°C has been constructed.