This paper proposes a new range alignment algorithm for airborne ISAR (Inverse Synthetic Aperture Radar) imaging of aerial targets. Initially, the airborne target echo envelope is analyzed, and based on the one-dimensional range profile, the authors intuitively give the reason for the serious envelope offset of the aerial target. Then, in the airborne ISAR imaging scenario of aerial targets, this paper optimizes the classical minimum entropy range alignment method. The improved minimum entropy algorithm not only effectively aligns the envelope but also has higher efficiency compared to the classical minimum entropy method. The experimental results demonstrate the effectiveness of the proposed algorithm.