<p>Friction stir additive manufacturing (FSAM) is an innovative additive manufacturing (AM) method. The various heat treatment conditions of aluminum-lithium alloys using this method have not been widely discussed. In this study, the microstructure evolution and mechanical properties of FSAM 2195 aluminum-lithium alloy in different heat treatment conditions (T3 and T8) were investigated. The results demonstrated that the heat treatment state of 2195 Al-Li alloys was minimally influenced by FSAM as the FSAM temperature exceeded the solid solution temperature. After conducting a single-pass FSAM experiment, a notable grain refinement was observed in the nugget zone (NZ) region compared to the base material (BM). The average grain size of the 2195-T3 alloy decreased from 6.1 to 2.9 µm, while the proportion of high-angle grain boundaries increased from 16.5% to 43.9%. Similarly, the average grain size of the 2195-T8 alloy decreased from 8.9 to 2.8 µm, with an increase in high-angle grain boundary from 37.6% to 59.2%. The tensile strength of the 2195-T3 Al-Li alloy reached 466 and 478 MPa in the NZ of single-pass and lap experiments, respectively. In comparison, the tensile strength of the 2195-T8 Al-Li alloy in the NZ could reach 452 and 481 MPa in single-pass and lap experiments, respectively. These results demonstrate the significant improvements in microstructure and mechanical properties were achieved through the FSAM process.</p>