Abstract: The mechanical properties, tribological properties and wear mechanism of AA2099 Al-Li alloy under solution heat treatment(SHT) and different aging treatments were investigated. The results reveal that with prolonged aging time, the average friction coefficient decreased first and then increased, and the lowest friction coefficient emerged when alloy was aged for 35 h(0.137).; The wear rate monotonously decreased, the lowest value wasobtainedfromthesampleaged for 96 h 1.7×10^-3mm³/(N·m). The wear mechanism of AA2099 Al-Li alloy at solid solution and different aging state in dry condition was abrasive wear and adhesive wear. Friction products had important influence on the friction coefficient, and friction products distributed homogeneously and continuously for sample aged for 35 h, which had good anti-friction effect. Mechanical properties combined with the wear-shallow structure stability mutual influenced the wear rate, when aging time was less than 35 h. Severe delamination in the wear-shallow area was observed. Variation of wear rate was not associated with H/E. As long as the aging time was more than 35 h, spalling was reduced and wear rate was positively related to the H/E change.