Abstract: The physicochemical properties,functional group structure and morphology of the biochar derived from crop straw（such as wheat,rice,rape straw）biomass were determined and analyzd using sealed oxygen limiting treatment to prepare the straw biochar based on orthogonal experiment method. The results showed that the temperature of carbonization was the most important factor effect on yield,pH value and ash content of straw biochar. And the carbon yield decreased with temperature,while pH value and ash content increased correspondingly,where carbon yield,pH value and ash content of rice straw was the best. Particularly,the biochar’s,obtained at 550 ℃ for 60 min,were rich in honeycomb pore structure and absorption vibration peak of the functional groups tended to be flat,which indicated the pore structure was abundant and stable.