Attitude information of space targets is an important basis for judging whether their working state is stable. In this paper, an attitude estimation method of space targets based on 3D reconstruction of ISAR image spindle is proposed. First, the Radon transform is used to extract the main axis and the sun plate axis of space targets from the ISAR image. Then, two ISAR images are used to reconstruct the three-dimensional axial, and the rolling axis and pitch axis of the target in the orbit coordinate system are acquired. Finally, the flying attitude of space target is calculated by Euler angle and coordinate system definition. This method can estimate the 3D attitude angle of space target more accurately. The validity of the method is verified by dynamic simulation data.