Abstract: The solubilities in acid and water of the polyphosphate obtained from phosphate at different temperatures were determined. The results showed that the solubility of polymeric phosphate decreased with the temperature increase; as the preparation temperature increased from 350℃ to 650℃, the water solubility and acid solubility decreased from 98.71% and 98.93% to 73.12% and 74.80%, respectively. Compared with the conventional water elution process, the effects of acid pickling, heating, oxidant HClO and centrifugal process on the ash content and the adsorption capacity of commercial phosphate-activated carbon were studied. The specific surface area of activated carbon were determined. The results showed that the ash content of activated carbon reduced from 6.24% to 1.49% when the samples were washed twice by HCl and oxidant HClO and then washed three times by water in 80℃ with centrifugal dehydration process compared the sample of water washing. And the specific surface area, pore diameter, pore volume, iodine adsorption value, methylene blue adsorption value and caramel decolorization were 1 503 m²/g, 3.656 nm, 1.361 cm³/g, 975 mg/g, 277.5 mg/g, 110%, which were larger than those of the water washed sample. Therefore, low-ash phosphate-activated carbon could be prepared at low temperature and by using the above demineralization process.