Concentrations and mineralization processes of organic phosphorus (Po) fractions in soils mixed with different organic materials (straw of rice and maize, manure of cattle and pig) of different C/N were studied by aerobic incubation experiment at 30℃ for 300 d. Results showed that soil Po contents increased at different degrees after organic materials were mixed; Po mineralization rates in treatments mixed with organic materials were higher than CK, and it mineralized quicker during the first 30 d of cultivation; The contents of organic phosphorus fractions in the treatments mixed with organic materials increased; Po fractions of CK mineralized smoothly, while active Po and moderately-active Po increased or fluctuated in treatments mixed with organic materials, moderately-resistant Po and highly-resistant Po mineralized quickly at initial stages of cultivation. Application of organic materials could promote transformation between different Po fractions, thus could improve phosphorus availability in soils.