Abstract: The study on the transformation of applied phosphorus and availability of residual phosphorus in wheat maize rotation was conducted on calcareous soils for three years The results showed that inorganic P accounted for 73 2%～96 4% of total soil P, Ca P was 79 1%～90 8% of inorganic P, Ca 10 P, Ca 8 P, Ca 2 P was 51 7～97 4%, 1 7%～44 8%, 0 9%～3 6% of Ca P, respectively and 24 6%～27 4%, 19 0%～20 4%, 12 4%～17 3% applied P was taken up by wheat and maize at each rotation, respectively The main fractions of residual phosphorus was Ca 2 P, Ca 8 P Most of absorbed P by crops was Ca 2 P, Ca 8 P, Al P, Fe P, that was important P resource at successive cultivating P fertilizer used together with manure increased the availability of residual P compared with P fertilizer applied alone Adding P fertilizer during three years successively cultivating increased the yield of wheat and maize