Productivity of blast furnace is dependent on quality of sinter. Quality of sinter is determined by its macrostructure. Structure of cake is dependent on conditions of sintering and properties of charge. Iron ore concentrates have been investigated. Electron scanning has been applied. Mathematical models have been developed which reflect connection between parameters of macrostructure of sinter and properties of charge. It has been found that high level of most technological properties of sinter is provided by large-pore structure with high share of pores more than 3 mm. Correct selection of composition of charge is necessary.