The "phase transfer-precipitation method" was adopted to conduct a pilot-scale experimental research on preparing nano-CaCO₃ using industrial solid waste phosphogypsum and CO₂ as raw materials. Through XRF, XRD tests, and SEM analysis characterization of the raw material phosphogypsum, its composition and content were determined, serving as the baseline for subsequent experiments. The pilot experiments investigated the adaptability and compatibility of key process conditions - including phase-transfer reaction, aging-separation reaction, carbonation precipitation reaction, and modification reaction - at a pilot scale. The results demonstrated that the Ca2+ conversion rates reached 90% for both phase-transfer and aging-separation reactions, and 95% for the carbonation precipitation reaction, indicating strong scalability of the optimized laboratory-scale conditions to pilot operations. The active nano-CaCO₃ produced at the pilot scale exhibited a pure calcite phase, with an average particle size of ~36nm, good dispersibility, and relatively uniform particle size distribution. The product’s key performance metrics either met or exceeded the specifications for plastic-grade nano-CaCO₃ (Type I) stipulated in the Chinese national standard.