Excess-sulfate phosphogypsum slag grouting material (EPSGM) has strong advantages for stabilizing the coral sand foundation, which requires establishing a groutability prediction model involving multi-factors to ensure better stabilization. Specifically, the grain size (d85) d 85 ) and water-to-cement ratio (w/c) w/c ) of the grout, particle size (D15), D 15 ), relative density (Dr), D r ), and fine content (FC) FC ) of coral sand, and grouting pressure (P) P ) are considered. The results show that the optimal particle size d 85 of EPSGM is 15.567 mu m. As the w/c increases from 1.0 to 3.0, the compressive strength of mortar (EPSGM + coral sand) decreases from 11.74 MPa to 0.32 MPa, and the California Bearing Ratio (CBR) value meets the typical requirements (>= 15%). The groutability criterion (N) N ) is positively correlated with the D15, 15 , w/c, , and P , while it is negatively correlated with the Dr r and FC , namely, the model writes: N = (1- 1- 0.071Dr)(1- D r )( 1- 1.54FC)0.024D15 FC ) 0.024 D 15 + 0.42(w/c) w / c ) + 0.897(P) P )- 0.86. Particularly, the predictive accuracy can d 85 attain a level of 87.50% for systems characterized by varying grain sizes ( D 15 >= 0.431 mm) and densities (Dr D r <= 0.67) of EPSGM stabilizing coral sand foundations. Furthermore, it also applies to other systems in literature that exhibit accuracy ranging from 33.33% to 62.50%. Therefore, the derived predictive model performs greater engineering relevance in informing the selection of grout factors.