Abstract: By using non-dispersive infrared (NDIR) method, continuous measurements of atmospheric CO2 were carried out at Mt. Waliguan where the environment is unaffected directly by local anthropogenic pollution. The characteristics of the atmospheric background CO2 concentration variation for the inland Plateau of China were presented in this paper. The results show that is has clearly diurnal and seasonal variations related to the grown cycle of the land vegetations, and that the pattern of seasonal variation correspond with the global geographical distribution of atmospheric CO2. It is found that the increase of CO2 concentration was at a lower rate in 1993, but at a great rate in 1994. Furthermore, the emission rates of CO2 from the Plateau grassland soil were also measured. The results show that the CO2 emission rate from the soil surface increases relatively in winter with the largest value of above 170 mg/m2·h when the photosynthesis of vegetation is essentially stagnant.