Abstract: NanoNiO particles were prepared by using the homogeneous precipitation method, and characterized by using Xray Diffraction (XRD), BET and transmission electronic microscope (TEM). The prepared nanoNiO particles were found to be spherical in shape, could be well dispersed, and demonstrated weak agglomeration. They generally had high purity and a fine crystal phase of cubic syngony with a mean size of ~7.5nm and specific surface area of 187.98m2/g. Meanwhile, evaluation of the catalytic activity of developed nanoNiO particles in pyrolyzing cellulose was carried out in comparison with that of microNiO, in the same conditions, using TGA. The results indicated that the activation energy in the presence of microNiO and nanoNiO reduced by 12.24kJ/mol and 22.42kJ/mol, respectively, in comparison with that of pure cellulose pyrolysis. This resulted in the initial temperatures of cellulose decomposition being 10℃ and 19℃ lower than that of pure cellulose, and the final char yield was further decreased. Compared to the microNiO, nanoNiO particles demonstrated an even superior activity.