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In order to ascertain the vertical distribution of sand layer CO2 concentration from the Alxa desert region as well as its impact on atmosphere CO2 and action on global carbon cycle, infrared CO2 monitor was used to perform 19 drilling holes to observe CO2 concentration day and night in the Nuoertu megadunes region, Shapotou trellis dunes region and Minqin barchan dunes region. The results showed that atmosphere CO2 concentration in Alxa desert region is lower than that in the sand layer of 1-5 m depths, which manifests that it is the source region of atmosphere CO2 and it releases CO2 day and night during warm seasons. The diurnal variation of sand layer CO2 concentration in extremely arid Alxa desert region shows obvious regularity: CO2 concentration of every depth varies from low to high to low from 8:00 am to next day 7:00 am. The diurnal variation of temperature is the main cause of diurnal variation of sand layer CO2 concentration, which are significantly correlated positively. In extremely arid desert region, sand layer moisture content is the main factor that determines sand layer CO2 concentration.