With synthetic wastewater, the authors investigated phosphorus recovery effect by seeded crystallization of precipitated calcium silicate, which is a byproduct of feldspar hydrothermal decomposition. The results showed that the remaining effluent phosphorus concentration could meet the wastewater discharge standard of 0.5 mg/L under the optimized conditions of seed concentration of 0.4 g/L, pH value of 8 and Ca/P molar ratio of 2. Phosphorus recovery efficiency of 79.5% showed that phosphorus recovery effect was still obvious after the precipitated calcium silicate was used for sixty times. The products obtained were analyzed by using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) techniques. The results show that the product of phosphorus recovery is hydroxyapatite (HAP). P₂O₅ content of more than 35% shows that the product can meet the standard of the rich phosphate rock and the precipitated calcium silicate is a potential and perfect seed of phosphorus recovery.