This study utilized commercially available soil conditioners and phosphogypsum as substrates, and phosphate- solubilizing bacteria as inoculants. Methods such as single-factor experiments, screening experimental design (Plackett-Burman design), and central composite design (CCD) were used to optimize the semi-solid fermentation process, combined with ammonia mineralization CO₂ technology to prepare a phosphogypsum soil conditioner. Results indicated that under conditions of a material-to-water ratio of 1∶5, an initial pH of 8.05, a temperature of 52.33°C, a cultivation time of 7 days, and an inoculum amount of 0.75%, the soluble phosphorus content in the soil conditioner reached 143.71 mg/L. Under conditions of a nitrogen-to-sulfur ratio of 3, a reaction temperature of 35°C, and a reaction time of 4 hours, the soluble sulfur content in the soil conditioner was 12.67 g/L. Phosphogypsum soil conditioner produced via semi-solid fermentation effectively adjusts soil pH, increases the content of soluble phosphates and sulfates, and improves soil carbon sequestration, which is of significant importance for soil improvement and fertility enhancement.