A pot experiment was conducted to study effects of ameliorants on soil properties and rice yield of acid sulfate paddy soil. Results show that soil pH, in the range of 3.47~4.90, was significantly and negatively correlated with exchangeable H and Al³ , but positively with soil available iron (Fe), sulfur (S). Compared with treatments CK and NPK, all the amelioration treatments showed varying significant effects of increasing crop yield and improving soil properties. Inorganic ameliorants, e.g. calcium magnesium phosphate, home-developed ameliorant, lime and alkali residue, were better than organic ones, such as humic acid, refined organic manure and alkaline organic manure. The amelioration effects were mainly reflected in higher soil pH, available Ca and available Mg, lower soil exchangeable H and Al³ , better environment for root growth and hence higher nutrient uptake by rice shoots and higher rice grain yield. To sum up, acid hazard (including active acid and potential acid) is the main limiting factor in rice production in acid sulfate paddy soil. Alkalescent and Ca- or P-rich inorganic substances, such as calcium magnesium phosphate, home-developed ameliorant, lime, etc. are proper ameliorants for acid sulfate paddy fields in agricultural practice.