The effects of Thermo-Mechanical Processing(TMP) on microstructure, hardness, electricity, intergranular and exfoliation corrosion resistance of extruded 2099 Al-Li alloy were investigated by microstructure observation, XRD analysis, hardness and electric conductivity testing. The results show that compared with the extruded 2099 Al-Li alloy after T83 heat treatment (540 °C/2 h solid solution, 3% pre-compression, 121 °C/14 h + 181 °C/48 h aging), the samples after TMP (540 °C/2 h solid solution, 400 °C/48 h overaging, about 50% large strain deformation, 540 °C/2 h solid solution)+(121 °C/14 h + 181 °C/48 h aging) recrystallize obviously. The HV hardness is a little lower(2006.2 MPa vs 1865.3 MPa) and so is dislocations strengthening. The electric conductivity and the intergranular corrosion resistance are improved significantly and the exfoliation corrosion resistance is also enhanced. This study shows that TMP is an effective method to improve the intergranular resistance with the hardness not greatly reduced