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Precipitation is one of the key factors that influence the soil respiration.A simulated precipitation experiment focused on response of wetland and farmland soil CO2 emissions to simulated rainfalls using a LI-8100 automated soil CO2 flux system(LI-COR, Lincoln, Nebraska, USA)was carried out. The dynamics of diurnal soil respiration rate and the correlations between soil respiration rate and soil temperature were also evaluated in this paper. Results showed that precipitation could stimulate wetland soil CO2 emission rate(P2 emissions in wetland soil were greater than that in farmland. The wetland soil cumulative CO2 emissions was greatest at 10 mm precipitation group, followed by 20 mm precipitation group, and control group had the smallest values. With the increase of rainfall，the wetland soil that had high organic carbon released high CO2 in short-term, and soil of low organic carbon(arid zone of northwest arid soil)had insignificant effect on soil carbon loss. Farmland soil CO2 emission rate was significantly correlated with soil temperature(0 cm, 5 cm)under 10 mm precipitation group(P2 was in accordance with the change of wetland soil. This finding indicated that precipitation was the important factor influencing the response of soil CO2 emissions in arid and semi-arid area.