In order to optimize the flux ratio and raw material structure of the belt roaster pelletizing process，and improve the strength of fresh pellets and the blast furnace adaptability of finished pellets，the acid and alkaline pellet system tests are carried out，and the optimal flux structure of the alkaline pellets is determined to be a mixed flux of“slaked lime + limestone powder”，and the ratio scheme of 2. 0% bentonite is used for the acid pellets. The performance of the pellets of the two schemes is verified in the trial production of the belt roaster，and the microscopic morphology and element distribution are characterized by scanning electron microscopy ( SEM) and energy dispersive spectroscopy ( EDS) . The results show that the iron grade of the acid pellets is 66. 20% ，the compressive strength is 2 500 N/P，the proportion of qualified particle size is 78. 24% ，the reduction expansion rate is 11. 4% ，and the reduction-index is 62. 68% . The iron grade of the alkaline pellets is 65. 41% ，the compressive strength is increased to 2 733 N/P，the proportion of qualified particle size is 76. 34% ，the reduction expansion rate is stably controlled below 15% ，and the reduction index is increased to 82%. The pellets of the two schemes meet the production indicators of the blast furnace，and the alkaline pellets are more suitable for the production mode of large pellets due to their high strength and low expansion. In addition，the microscopic morphology and element distribution characteristics of acidic and alkaline pellets are clarified by scanning electron microscopy observation and energy spectrum analysis. The results not only provide an important basis for improving pellets quality，but also provide a reference for the design，production and operation of the belt roaster pellets process.