Main physical property and service performance on aluminum electrolysis cell of five groups anode cover materials with different particle composition was examined. The results showed that with the decrease of particle size, bulk density increased from 1.56 g/cm3 to 1.62 g/cm3 and then decreased to 1.52 g/cm3, and repose angle decreased from 41.2░to 38.3░. On the whole thermal conductivity at working temperature decreased as particle size decreased, it decreased from 1.21W/mĚK to 0.91W/mĚK and then decreased slowly. Covered material surface average heat dissipation decreased when used on cell as particle size decreased, when particle size of cover material reduced to a certain extent, covered material surface average heat dissipation decreased to 22~23 mV, continuing decreasing particle size, no obvious insulation improving was got. Through the study, one cover materials was choen, and it particle composition was: <0.25mm 29.85%, 0.25mm-2mm 30.29%, 2mm-8mm 29.65%, and >8mm 10.21%.