In order to study the influence of straw biomass pyrolysis in a rotating bed reactor under different carrier gas conditions, including no carrier gas, the tail gas and N2, biomass pyrolysis was tested based on the reactor. The biochar, biooil and syngas were collected respectively, and the yield rates were calculated. The biochar’s calorific value and elements were analyzed; biooil’s calorific value, water content and elements were analyzed; the syngas’ composition and content of organic compounds were analyzed by using gas chromatography. Passing the tail gas can reduce the generation of bio char, increase the production of bio oil, and the higher calorific value of bio char was, the higher carbon content was. The water content of bio oil was decreased, and organic matter content was increased. But when the calorific value of bio oil decreased, the content of light organic matter was the highest in syngas. The tail gas can take away pyrolysis gas more quickly or participate in the pyrolysis of twotime reaction. Biomass react was the most adequate, and tail gas can increase the activity of H; reduce water content, but no way to remove oxygen elements, so the oxygen elements retained in the bio oil. Nitrogen can reduce production of biochar, increase bio oil production and calorific value, and change a little carbon content of biochar, bio oil moisture and organic matter content, but the calorific value of the bio oil greatly increased; the light organic matter content in syngas was the least. Nitrogen can reduce twotime reaction and pyrolysis gas can quickly leave the reactor.