In order to reveal the law of gas evolved from the pyrolysis and gasification processes of stalk biomass, the typical corn stalk in the rural areas of northeastern China was utilized as the pyrolysis experimental material. Based on the self-established pyrolysis and gasification experiment system in tube furnace, the release characteristics of CO, H2, CO2, CH4, CnHm and other small-molecule biomass gas components during the pyrolysis of corn stalk in nitrogen atmosphere and gasification in oxygen-containing atmosphere were systematically studied. The effects of different pyrolysis and gasification temperatures on the release characterization and yield of each syngas component were compared. The experiment results indicated that CO and CO2 were the first small molecule syngas products released during corn stalk pyrolysis. When the temperature was increased, CH4 and H2 gradually appeared in the syngas, and with the increase of pyrolysis temperature, the peak yield of CO first appeared in the heating stage while the peak yields of CO2, CH4 and H2 appeared almost simultaneously in the constant temperature stage. With the increase of pyrolysis temperature, the volume fraction of CO during pyrolysis was hardly changed. However, the CO2 proportion was decreased with the increase of temperature. The CH4 volume fraction was increased with the increase of pyrolysis temperature between 400℃ and 500℃, and the content basically stabilized at 13% after 500℃. In the oxygen-containing atmosphere with 8% O2 and 92% N2, the volume fraction of CO2 produced by corn stalk gasification showed a trend of first increasing and then decreasing with the increase of gasification temperature, while the volume fraction of CO was increased with the increase of temperature, indicating that the high temperature was more conducive to the release of CO, and the low temperature was favorable to the CO2 production.