[Objective] The effect of combining organic fertilizer with a water retaining agent on the hydraulic properties of brown soil in the tillage layer was analyzed in order to provide a technical approach and theoretical basis that can be used to improve brown soil tillage by finding the optimal organic fertilizer application amount and the optimal water retaining agent ratio. [Methods] A brown soil topsoil from Shanxi Province and a split-plot experimental design were used for the experiment. The main plot treatments were the amount of organic fertilizer applied: F₁ (0 t/hm²), F₂ (45 t/hm²), F₃ (60 t/hm²), and F₄ (75 t/hm²), and the subplot treatments were four water-retaining agent applications: B₁ (0 kg/hm²), B₂ (300 kg/hm²), B₃ (600 kg/hm²), and B₄ (900 kg/hm²). The effects of the amount of organic fertilizer and water-retaining agent on the soil water characteristics curve, specific water capacity, and available water content were analyzed. [Results] ① Soil water-holding capacity, water-supply capacity, and the effective water content increased in the organic fertilizer combined with water-retaining agent treatments compared to the water-retaining agent alone treatments. ② The effects of organic fertilizer combined with a water-retaining agent on soil hydraulic properties varied depending on the amounts of organic fertilizer applied. The water-holding capacity and water-supplying capacity of the test soil at low suction section followed the order F₃ > F₂ > F₄ > F₁, and the same was true for the effective water content. ③ Under the F₃ treatment, the water holding capacity and water supply capacity of the soil first increased and then decreased as the water retaining agent application rate increased. There was a parabolic relationship between the effective soil water content and water-retaining agent application ratio (R²=0.949 3). [Conclusion] The improvement effect was greatest under the treatments with a medium amount of organic fertilizer (60 t/hm²) combined with a water-retaining agent and the optimum proportion of water-retaining agent under this amount of organic fertilizer was 0.91%.