Abstract: A series of biochars obtained from rice straw and rice husk were prepared under different pyrolysis temperatures of 300, 400, 500, 600 or 700℃ under the oxygen limited condition. The effects of materials and temperatures on the surface properties of biochars obtained from two materials under different temperatures were evaluated. BET specific surface area analyzer was used to characterize the BET specific surface area. Qualitative and quantitative analysis by Fourier-transform infrared spectroscopy (FTIR) and Boehm titration were used to estimate the species and amount of the surface functional groups of biochars. The results showed that the BET specific surface areas of the biochars made from rice husk (named RC-H) of 300℃, 400℃ or 500℃was higher than that of the biochars made from rice straw (named RC-S) at the same temperature. But the BET specific surface area of RC-S was higher than that of RC-H made at 600℃ or 700℃. With increasing pyrolysis temperature, the BET specific surface of both RC-S and RC-H increased obviously. RC-S with the highest surface area was obtained at 600℃ and RC-H at 700℃. The results of FTIR analysis indicated that the characteristic absorption peak of the biochars made from the two materials under the same pyrolysis temperature were the same, and there were no obvious differences between the species of functional groups, but the surface functional groups on RC-S were more abundant than RC-H made under the same pyrolysis temperature. Aromatic nucleus were formed during the pyrolysis process, and the degree of aromatics increased and stability enhanced with pyrolysis temperature. The change of the functional groups on the surface of the biochars made from the two materials with pyrolysis temperature was similar, which mainly showed that the alkyl group disappeared with the increasing temperature, methyl (-CH3) and methylene (-CH2) gradually disappeared, aromatic compounds increased and aromatic enhanced. The results of Bohem titration showed that the total quantities of surface functional groups and basic functional groups of RC-S were more than those of RC-H which made under different pyrolysis temperatures, but the quantities of acidic surface functional groups of RC-S were less than those of RC-H. With the increasing pyrolysis temperature, the change of the surface functional groups of the biochars made from the two materials was similar. The total quantities of surface functional groups and the contents of acidic surface functional groups decreased while the contents of the basic functional groups increased.