Abstract: Acid sulfate soil (ASS) is the typical type of lowing-yielding fields in South China. It has a great signification to ameliorate and utilization reasonably. [Method]In this study, a pot experiment was used to evaluate biochar(produced by slow pyrolysis of citrus branch) Regulates acid sulfate soil with different application rates. The experiment consisted of five treatments with four replicates: NPK; NPK+0.5%BC(the rate of biochar and dry soil); NPK+1%BC; NPK+2%BC; NPK+4%BC. [Result] Results indicated that with the different application rates of biochar, The variation tendency of soil pH and OM showed consistently. The Total Nitrogen(TN) elevated gradually with the increasingly used of biochar. The maximum value was 15.1% with 4% BC treatment, but the average increasing rate became decrease. The ammonia nitrogen and the nitrate nitrogen have the opposite trend. Which from 11.46 declined to 0.96 mg?kg-1 and from 8.37 declined to 5.14 mg?kg-1 respectively. Those were benefit to depollution from agriculture, but may cause innutrition of available nitrogen during peak-growth period. The yield of leaf mustard and some other indexes have the inflection point when the dosage increased to 4%. such as the quantity of soil microorganism. The soil amount of bacterial were improved, but both the quality of vegetable and the fungus in soil have no regularity with different application rates of biochar. [Conclusion] moderate amounts of citrus branches could get greater environmental and agriculture effect in ASS though this study. Key words: biochar; acid sulfate soil; soil regulate; non-point pollution