The alkali solution absorption method was used in this study. The observation, which lasted 2 years from September 1999 to August 2001, found CO₂ emission different from what other scholars observed in other areas, that is to say the volume of CO₂ emitted in the daytime was lower than at nighttime. The research showed that change in CO₂ emission from Loess soil in Xi'an tended to keep pace with the change in temperature, but lag a bit in time. CO₂ emission from Loess soil in Xi'an varied with the season, being the highest in summer, moderate in autumn, and the lowest in winter. The volume of CO₂ released per day was found to be the highest in July, over 8 g/(m²·d), the second highest in August, and the lowest in December, January and February, less than 0.5 g/(m²·d). Statistic analysis showed the emission was in extremely obvious positive correlation with temperature. CO₂ emission also varied with the vegetation. Generally speaking, CO₂ emission is high on the bare ground, but low on the woodland and grassland. The experiment showed that vegetation played an important role in slowing down the release of soil carbon and protecting the environment. The protection of vegetation and enhancement of the ecosystem is one of the effective measures to curb CO₂ in the atmosphere. Therefore, restoration and construction of forests, and enlargement of Carbon sinks on the continent is an important aspect in the environment construction from now on.