[Objective] While hydropower construction promotes clean energy development, it significantly []impacts the ecological environment, particularly in ecologically fragile areas such as the Jinsha River arid—hot valley, where topsoil resource scarcity, severe soil degradation, and vegetation restoration difficulties are increasingly prominent, urgently requiring the establishment of efficient soil amelioration technology systems. [Methods] A field soil maturation experiment was conducted at the slag site of the Xulong Hydropower Station in the upper reaches of the Jinsha River from the early rainy season in May 2023 until after the autumn harvest in November 2024, covering one full growing season (approximately 18 months). A complete experimental design was adopted, comprising nine treatments: T1 (control, basal fertilizer only), T2 (sowing soybean seeds at 10 kg/ha), T3 (texture improvement), T4 (organic matter amendment at 5 g/kg soil), T5 (organic matter amendment at 10 g/kg soil), T6 (soybean + organic matter at 5 g/kg soil), T7 (soybean + organic matter at 10 g/kg soil), T8 (soybean + texture improvement + organic matter at 5 g/kg soil), and T9 (soybean + texture improvement + organic matter at 10 g/kg soil). Each treatment was replicated three times, resulting in a total of 27 experimental plots., Fourteen soil physicochemical properties in the 0-100 cm?slag soil?were systematically monitored, and LSD multiple comparison along with correlation analysis were used to reveal the amelioration effects and synergistic mechanisms of different maturation measures. [Results] The results indicated that the composite treatment T9 (soybean + texture improvement + 10 g/kg organic matter) demonstrated the most effective improvement, showing the highest proportion of indicators that were significantly superior to other treatments. Specifically, compared to the control, the contents of organic matter, total nitrogen, and available phosphorus increased by 112.2% (from 15.16 g/kg to 32.17 g/kg), 102.8% (from 1.45 g/kg to 2.94 g/kg), and 128.8% (from 1.49 mg/kg to 3.41 mg/kg), respectively. Meanwhile, the soil bulk density decreased by 45.5% (from 1.30 g/cm3 to 0.71 g/cm3), while the water-stable aggregates increased by 66.5% (from 55.56% to 92.51%). Correlation analysis among soil physicochemical properties revealed that 69.2% of the indicator pairs showed significant correlations (P < 0.05). The correlation coefficients between organic matter and major nutrient indicators all exceeded 0.85, whereas pH showed significant negative correlations with these fertility indicators (P < 0.05), indicating a synergistic co-variation pattern where the enhancement of organic matter was accompanied by nutrient activation and soil acidification.[Conclusion] This study confirms that the synergistic model of "legume nitrogen fixation–organic cementation–physical structure optimization" can effectively overcome the multiple constraints of soil maturation in engineering slag fields within the dry-hot valley, providing a reliable technical strategy and scientific basis for rapid ecological restoration of hydropower projects in this region.