The characteristics of UO2 pellets containing PVA-Al(III) complex as a function of sintering temperature and sintering time under H2 reduction atmosphere and CO2 oxidation atmosphere were investigated. Under reduction atmosphere the sintered density was increased with sintering temperature and sintering time but the sintered density under oxidation atmosphere was reversely decreased due to the solarization. In a view of the pore size variation although the pore size of pure UO2 pellet under reduction and oxidation atmospheres was not changed due to the formation of fine pore of 2-4 ${mu}{ extrm}{m}$ but the pore size of UO2 pellets containing PVA-Al(III) complex appeared as the fine pore of 2-4 ${mu}{ extrm}{m}$ was reduced. while the macro pore of 15-30 ${mu}{ extrm}{m}$ was much more increased. In a view of grain size variation the grain size of UO2 pellets containing PVA-Al(III) complex was increased up to 33-36 ${mu}{ extrm}{m}$ whereas the grain size of pure UO2 pellet was regular grain size of 1-5${mu}{ extrm}{m}$ and large irregular grain size of 20-50${mu}{ extrm}{m}$. With increasing the sintering temperature and sinterig time the large grain size was much more increased and changed to regular shape comparing the small grain size was reduced