<p>A new phosphogypsum-concrete combined wallboard was designed by consisting reinforced concrete frame and 59.3% phosphogypsum filler. The seismic performances of combined wallboards were analyzed through damage modes, hysteresis curves, skeleton curves, ductility, stiffness degradation, and energy dissipation capacity. The experimental results shown that the damage of the combined wallboard originated from the buckling of reinforced concrete frame and the damage of phosphogypsum filler. The concrete and phosphogypsum filler on the frame columns were crushed and dislodged from the wall, and the steel reinforcement was yielded, decreasing the bearing capacity. The load-displacement curve of the combined wallboard had fuller shape and the stiffness degradation curve was three-segmented with higher energy dissipation capacity. The displacement ductility coefficient of the combined wallboard was between 2.5 and 2.8, and the ultimate displacement angle was 1/38.5, exhibiting good deformation capacity and ductility. Additionally, the bearing capacity of combined wallboard was better predicted by the equivalent compression zone model, and the error between the theoretical calculated and experimental results was within 9.4%. Moreover, a refined finite element model of the combined wallboard was established, well predicting the skeleton curve and damage mode of combined wallboard. The compressive and tensile stress distributions were agreement with the principle of equivalent compression zone.</p>