Soil CO₂ is a key driving factor in the karst carbon cycle. The soil profile of Yaji karst test site in Guilin, Guangxi Province was selected as a case study. High-resolution monitoring technology was employed to measure temperature, moisture, and CO₂ levels at various soil depths. The analysis focused on the dynamic mechanisms and influencing factors of CO₂ content within the soil profile. At the seasonal scale, soil temperature is the primary factor influencing soil CO₂ concentration. Soil temperature corresponded with atmospheric temperature, exhibiting pronounced diurnal variations at the surface level, while deeper soil layers displayed continuous changes over multiple days. On long time scales, higher soil temperatures correspond to increased soil CO₂ concentrations. Conversely, on shorter time scales, soil moisture is the primary factor affecting soil CO₂ levels. Prior to precipitation, soil moisture levels are low. Following precipitation, soil CO₂ is released in pulses. Conversely, when soil moisture is high, precipitation results in a decrease in soil CO₂ content. Notably, under drought conditions, precipitation can substantially elevate soil CO₂ levels, a phenomenon known as the "birch effect". Under varying precipitation scenarios, different precipitation intensities exert distinct effects on soil CO₂ content. Following a brief period of heavy rainfall, CO₂-10 levels increased rapidly, while CO₂-40 and CO₂-90 exhibited minimal changes. Prolonged precipitation resulted in an initial rise in CO₂-10, followed by a decline, whereas CO₂-90 gradually decreased. Changes in soil CO₂ content are influenced by the characteristics of soil stratification. The root systems of plants in the topsoil are dense, resulting in elevated CO₂ levels. Conversely, deep soils exhibit low porosity and diffusion rates, leading to an increase in CO₂ content with depth. The findings provide scientific guidance for understanding the global karst carbon cycle.