Abstract: To investigate the effect of annealing temperature on the microstructure and mechanical properties of Fe- 28.0Mn-6.2Al-1C-4Ni-3.2W low density steel, the specimens were subjected to annealing at 550℃(A550) and 650℃(A650) for 30 minutes followed by air cooling. The mechanical properties and microstructural evolution were analyzed using room-temperature tensile tests, SEM, EBSD and TEM. The experimental results indicate that the annealing temperature significantly influences the microstructure and mechanical properties of Fe-28.0Mn-6.2Al-1C-4Ni-3.2W low density steel. When the annealing temperature increases from 550 ℃ to 650 ℃, both the strength and ductility of the sample decrease. The yield strength, tensile strength, elongation and strength-ductility product of the A550 specimen are 545 MPa, 973 MPa, 62.4% and 60.7 GPa·%, respectively. The strength-ductility product of A550 specimen is 40% higher than that of A650 specimen, indicating superior overall mechanical performance. The differences in average grain size between the two annealed specimens are minimal, with no precipitates observed in either case, suggesting that grain refinement and precipitation strengthening of the test steel are not dominant strengthening mechanisms. The geometrically necessary dislocation (GND) density of A550 specimen before and after tensile test is higher than that of A650 specimen, the dislocation strengthening effect of A550 specimen is more significant. After tensile test, the A550 specimen exhibits finer and more uniformly distributed slip bands, whereas the A650 specimen shows wider and irregularly spaced slip bands. The refinement of slip bands in A550 specimens is accompanied by high dislocation density, leading to more pronounced dislocation strengthening effect and higher strength. Simultaneously, uniformly distributed slip bands promote uniform stress distribution, avoid stress concentration, delay necking, and achieve better ductility. Ultimately, the A550 specimens exhibit an excellent combination of strength and ductility. This study provides valuable insights for optimizing the annealing process and engineering applications of such low density steels.