Irrigated agriculture can enhance the potential of grain production and has become an important development direction of global agriculture. However, this land use conversion will inevitably affect the stability of dryland soil, especially the carbon cycle. However, in the process of converting dry land into water, the change of soil carbon flux and its mutual feedback mechanism with environmental factors are still unclear. Therefore, the field simulation experiment was used to monitor the change of soil carbon flux for 7 consecutive days. To evaluate the short-term impact of water improvement in dry land on soil carbon pool composition and environmental drive. The results showed that: ① the soil carbon flux and temperature in dry land and paddy field showed a single peak curve with high day and low night, and the peak value of carbon flux and temperature appeared around 13:00 every day. However, the soil carbon flux in paddy field is slightly higher than that in dry land. ② Soil soluble organic carbon (DOC), microbial biomass carbon (MBC), oxidizable organic carbon (EOC), inert organic carbon (ROC), total organic carbon (TOC) and soil carbon pool management index all showed a downward trend in a short time after water improvement in dry land. Among them, soil microbial biomass carbon and oxidizable organic carbon decreased by 28.55% and 29.09% respectively. ③ Soil water content, microbial OTU number and carbon pool content are the key factors affecting the change of carbon flux rate (P < 0.05), while soil temperature and physical and chemical properties are the main factors restricting soil carbon pool (P < 0.05). Agricultural activities are one of the important carbon sources, so it is necessary to study the induction of large-scale drought and water change.