Little information is available on biochar effects on phosphorus (P) availability in soil. Effects of the rice- residue-chars pepared at 300℃, 450℃ and 600℃, and the poplar-branch-char prepared at 450℃ with the rates of 5, 15 and 40 g/kg, respectively on P availability in paddy soils were studied by using indoor incubation. The Olsen-P content increased significantly in paddy soil amended by the rice-residue-char compared with the poplar-branch-char under the same conditions. There were no significant differences in Olsen-P contents of paddy soils amended by the rice-residue-chars prepared at 300℃, 450℃ and 600℃, respectively. The results demonstrated that P availability in paddy soil is significantly affected by the amended biochar prepared by different feedstock and by application rate of the amended biochar, but not affected by the amended biochar prepared at different temperatures.