Abstract: Abstract: In this study, to investigate the impacts of feedstocks, pyrolysis temperature and sieving treatments (before pyrolysis and after pyrolysis) on biochar properties and cadmium adsorption capacity, as well as the relationship between biochar properties and cadmium adsorption capacity, two kinds of agricultural solid wastes (pig manure, and rice straw) were pyrolyzed at five temperatures (300, 400, 500, 600, 700 ℃ ). The effects of different treatments on the physicochemical properties such as yield, ash content, pH, element composition (C, H, N, O) and BET specific surface area of biochars were investigated. The biochars were also characterized by scanning electron microscopy（SEM）, X-ray diffraction (XRD) and Fourier transform infrared spectro graph (FTIR). The cadmium adsorption capacity of biochars with different treatments was determined by a batch experiment. The relationship between physicochemical properties and cadmium adsorption capacity of biochars was also analyzed. The results showed that: 1) With increasing pyrolysis temperature, the yield, N, H, O content and H/C molar ratio of biochars decreased, and the pH, ash content and BET specific surface area increased. At the same pyrolysis temperature, the yield and ash content of pig manure (PM) biochars were higher than that of rice straw (RS) biochars, while the pH value and BET specific surface area were opposite. Biochars with different treatments had lower O/C and (O+N)/C molar ratios than that of raw materials, indicating that the polarity of biochars was weakened during pyrolysis process. 2) The effect of raw material on the cadmium adsorption capacity of biochar was significant. The cadmium adsorption capacity of rice straw biochar (the maximum adsorption capacity was 69.2 mg/g) were better than pig manure biochar (the maximum adsorption capacity was 36.4 mg/g), and increased with the pyrolysis temperature. The cadmium adsorption capacity of PMCA (PM is pig manure, C expresses biochar, A expresses biochar sieved by 0.25 mm) was not significantly increased with pyrolysis temperature. The higher pH value and BET specific surface area may be responsible for its better cadmium adsorption capacity of straw biochar. There was no obvious tendency for the cadmium adsorption capacity of biochars with different sieved treatments (before and after pyrolysis). 3) Correlations between the yield and ash content of different biochars were significantly negatively correlated, and yield showed highly significant and positive correlation with H/C. The ash content of biochars was positively correlated with pH value. Rice straw biochar, with higher pH value, had lower ash content than that of pig manure biochar, which can be explained by the different composition of ash contents, as XRD results showed that the minerals of rice straw biochar mainly consisted of sylvine. 4) The cadmium adsorption capacity of biochars (RSCB, RSCA and PMCB, RS is rice straw, B expresses raw material sieved by 0.25 mm befre pgrolysis) was significantly negatively correlated with yield and H/C molar ratio. There were positive correlation coefficient between adsorption capacity and ash and BET specific surface area, and the cadmium adsorption capacity of RSCB was significantly correlated with its ash content, and that of RSCA was significantly correlated with its BET specific surface area. The cadmium adsorption capacity of RSCA, RSCB had high correlation with pH value. It indicated that the yield and H/C were important for the cadmium adsorption capacity of these three kinds of biochars, and ash content, the BET specific surface and pH were of secondary importance. However, the cadmium adsorption capacity of PMCA was not correlated to all physicochemical properties, which may contribute to the inhomogeneity of the raw materials.