Abstract: In order to understand the emission of flue gas pollutants from open burning of crop straws in Inner Mongolia Autonomous Region, a self-designed biomass combustion system was used and typical crop (sunflower and corn) straws in Inner Mongolia were taken as the research objects to conduct indoor simulated combustion experiment. The emission characteristics of straw burning were studied by comparing the differences of emission factors of CO, CO₂, NO_x, C_xH_y and PM_2.5 in different areas. The results showed that the emission factors of CO, CO₂, NO_x, C_xH_y and PM_2.5 of sunflower straw were (344.71±66.36), (1 147.73±229.01), (3.20±0.62), (138.48±28.22) and (0.97±0.20) g/kg, respectively, and the emission factors of CO, CO₂, NO_x, C_xH_y and PM_2.5 of corn straw were (319.69±52.27), (1 178.75±149.00), (1.29±0.04), (57.83±9.45) and (1.44±0.17) g/kg, respectively. The emission factors of PM_2.5 of crop straws in different areas were (0.23±0.11) - (3.26±0.16) and (0.53±0.35) - (2.91±1.69) g/kg in flaming and smoldering, respectively; the emission factors of CO were (162.66±15.94) - (381.65±81.74) and (235.29±34.43) - (569.80±165.72) g/kg in flaming and smoldering, respectively; the emission factors of CO₂ were (1 094.96±182.04) - (1 866.22±377.83) and (725.10±107.71) - (1 409.43±82.32) g/kg in flaming and smoldering, respectively. The emission factor of CO₂ was higher in flaming than that of smoldering, and the emission factors of CO, NO_x, C_xH_y and PM_2.5 were higher in smoldering than those in flaming.