To reveal the dislocation evolution law of 7A85 aluminum alloy during the aging process, the influences of aging temperature and aging time on dislocation density was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the dislocation density is reduced rapidly from 3.59×10¹⁴ m^-2 to 0.62×10¹⁴ m^-2 (decreased by 82.7%) when the aging temperature increases from 80 °C to 160 °C. Similarly, the dislocation density is decreased by 41% with the extension of aging time, and it tends to a steady value after aging treatment for 12 h. Furthermore, the TEM micrographs indicate that dislocations tend to form a low-energy dislocation cell and gradually turn into subgrain. Finally, on the basis of the results of XRD and TEM, the dislocation densities of dislocation entanglement, dislocation cell and subgrain were quantified.