【Objective】Soil organic carbon (SOC) pool, the largest C pool in terrestrial ecosystems, can achieve long-term C sequestration. SOC plays a vital role in the global C cycle and is a key link in achieving C peaking and C neutrality goals. Humic acid (HA) is one of the most important and more stable components of soil organic matter, representing a more stable soil C pool. The vegetation coverage type of regional soil affects the quantity, quality and composition of HA, and further affects its aggregation characteristics. In this study, HA in surface soil under bamboo forest (Altitude 580 m) and broad-leaved forest (Altitude 280 m) in Jinyun Mountain, Chongqing, was taken as the research object, and then surface properties and aggregation characteristics of these two HA were clarified. 【Method】The structural characteristics were evaluated by element analysis, thermal gravimetric analysis, and Fourier infrared spectroscopy. Combined with dynamic light scattering and zeta potential measurement, the aggregation kinetic characteristics of these two HA colloids induced by Na+, Mg2+ and Ca2+ were studied and compared. 【Result】It was found that HA in bamboo forest soil had higher C/N, C/H, stronger thermal stability and aromatic infrared absorption characteristic spectra, indicating HA in bamboo forest soil had more aromatic functional groups, more complex structure, and higher humification degree. The results of dynamic light scattering showed that the critical coagulation concentrations of Na+, Mg2+, and Ca2+ for the HA colloids of bamboo forest soil were 1 097.9 mmol?L-1, 8.6 mmol?L-1, and 5.1 mmol?L-1, respectively. The HA colloids of broad-leaved forest soil did not aggregate in the Na+ system, and the critical coagulation concentrations in Mg2+ and Ca2+ systems were 80.7 mmol?L-1 and 20.2 mmol?L-1, respectively. The zeta potential of HA in bamboo forest soil was much lower than that in broad-leaved forest soil. The absolute value of the zeta potential of HA in bamboo forest soil was 3.43 times that of HA in broad-leaved forest soil, which could be used to explain the difference in aggregation characteristics between the two. The sensitivity of the HA in bamboo forest soil to three cations is much higher than that of HA in broad-leaved forest soil, which can quickly aggregate and form larger particle sizes. 【Conclusion】The change of coverage vegetation types will cause the corresponding change of HA properties in surface soil. The humification degree of HA in high-altitude bamboo forest soil is higher, and the sensitivity to cations is also higher. The results of this study provide an important reference for understanding the formation and stability of HA after organic matter input into soil.