Abstract: This paper focuses on Two Dimensional (2D) geometric feature inversion method of midcourse targets, serving for the target recognition problem of ballistic missile defense system. Based on the figuration characteristic of midcourse targets, a stable characteristic quantity, which describes the 2D geometric configuration of target, is proposed. The characteristic quantity is independent on the target attitude variation and radar work condition. Then the expression form of 2D geometric feature in radar image is analyzed with respect to different intervals, the mapping relationships between ISAR images under various target attitudes and the 2D geometric feature of target are established, and an 2D geometric feature inversion method for midcourse targets based on ISAR image is proposed. The proposed method can stably estimate the 2D geometric feature of midcourse targets under all attitudes during the midcourse flight, which is verified by the simulation experiments with electromagnetic computed data and measured data in anechoic chamber.