Abstract: The effect of phosphorus (0, 1, 5 and 20 mmol/L) on biomass and ion regulation was investigated using Zoysia matrella under salt stress (300 mmol/L NaCl) in hydroponic solution. Both phosphorus deficiency and salinity retardation of plant growth were more severe under P deficiency than under salt stress. With or without salt stress, phosphorous promoted the growth of Z. matrella, but too high a P concentration (20 mmol/L) led to growth inhibition. P addition within reasonable amounts promoted root growth and tended to increase leaf Na⁺ secretion but inhibit Na⁺ transport from root to leaf. It also restricted leaf Na⁺ accumulation and increased leaf K⁺ accumulation, leading to a decrease in leaf Na⁺/K⁺. All of these factors together help improve salt tolerance.