In order to explore the application of biochemical fulvic acid (BFA) in soil structure improvement, the influence of BFA on soil physical properties and water movement characteristics under different concentrations was studied by adding BFA to soil. The results showed that: (1) As the proportion of BFA increased, the number of water-stable aggregates>0.25 mm in soil increased significantly. When the proportion was 20 g/kg, R_0.25, mean weight diameter (MWD) and geometric mean diameter (GMD) increased by 284.98%, 105.64%, and 35.06%, respectively, the fractal dimension decreased by 2.17%. (2) Under the influence of temperature and pH change, the absolute value of Zeta potential first increased and then decreased as the application ratio increased. When the application ratio was 20 g/kg, the absolute value of Zeta potential increased by 11.77% and 59.70%, respectively. (3) Applying BFA to soil could enhance soil infiltration capacity, increase cumulative infiltration and infiltration rate, and accelerate soil moisture front migration. Moreover, with the increase of application ratio, soil moisture infiltration capacity was significantly enhanced. Cumulative infiltration and was increased by 28.83%. The three infiltration models could simulate the soil water infiltration process well.