The objective of this study was to explore the transformation of water-soluble phosphate fertilizer in calcareous soil. A soil incubation experiment was conducted. Different amounts of superphosphate(P 0，6.25，12.5，25，50 and 100 mg/kg dry soil)were added to the soil(recorded as P0，P6.25，P12.5，P25，P50 and P100 treatments)，and the soil humidity was maintained at 70%～80% of the field capacity. The soil was incubated in a constant temperature incubator at 25℃ for 120 days. Continuous sampling was performed on days of 1，3，7，15，30，60 and 120 during the incubation period. The contents of Olsen-P，CaCl2-P and inorganic phosphorus fractions in soil were determined. The results showed that the content of Olsen-P and CaCl2-P in calcareous soil was significantly increased by applying superphosphate. Within a certain incubation time，the proportion of superphosphate transformed into Olsen-P and CaCl2-P in soil did not change with the change of fertilization amount. The soil available phosphorus was decreased significantly in the first 7 days of incubation，and then decreased slowly. The superphosphate applied to the soil was mainly transformed into Ca2-P and Ca8-P(the sum of the two was about 90%)，followed by Al-P and Fe-P(the sum of the two was about 10%). In the short term，the contents of O-P, Ca10-P were relatively stable. With the extension of incubation time，Ca2-P gradually transformed into Ca8-P，and the transformation rate was fast in the first 30 days of incubation，and then slowed down. With the increase of phosphorus fertilizer application，the time required for Ca2-P transform into Ca8-P gradually prolonged. The contents of Olsen-P and CaCl2-P were significantly positively correlated with the contents of Ca2-P，Ca8-P and Al-P in soil inorganic phosphorus fractions. The stepwise regression analysis showed that Ca2-P was the main source of soil Olsen-P and CaCl2-P.