Semi-coke has the advantages of high calorific value, low ash content, and low sulfur content, but low volatile content and high ignition temperature. Straw has low calorific value, high volatile content and low ignition temperature. The ignition characteristics between the semi-coke and straw are complementary. In order to investigate  the emissionsof sulfur oxides, nitrogen oxides and ash melting performance of semi-coke mixed with biomass fuel combustion, the fixed bed experimental system was used to study three kinds of semi-coke from different regions, wheat straw, corn straw and the mixed fuel pollutant emission characteristics respectively, and the influence of mixing proportion and combustion temperature on pollutant discharge, and the ash melting performance was analyzed by the ash fusion analyzer. The results show that the release of sulfur oxide and nitrogen oxide from the mixed fuel is related to the mixing conditions, and the composition of raw materials and combustion process affect the pollutant release characteristics. When 20%-30% corn stalk is mixed into the fuel, the mixed fuel shows a good sulfur fixation effect, and the nitrogen release rate is about 0.04%. Sulfur precipitation is significantly promoted by raising the combustion temperature. When the combustion temperature is lower than 1 000 ℃, the mixed fuel of Fugu semi-coke and corn stalk have good self-sulfur fixation characteristics, and the nitrogen release rate is lower than 0.02%. In addition, the ash melting characteristic temperature of the mixed fuel is between the temperature of original semi-coke and corn stalk, which has a certain relationship with the mixing ratio. The anti-slagging property of semi-coke is significantly better than that of corn stalk, which is helpful to improve the slagging property of straw by mixing. The results of this study provide theoretical reference for clean utilization of semi-coke and biomass.