The study of the impulse coupling characteristics is the basis for analyzing the scheme of laser cleaning space debris. Due to the influences of atmospheric transmission and diffraction limit, the laser spot size is close to the size of the irradiated particles, which are in centimeter order of magnitude. Most of the space debris are non-planar because of explosion, disintegration, and collision. Therefore, it is the key of laser cleaning space debris to study the impulse coupling characteristics of non-planar debris irradiated by a great spot. Taking a typical non-planar space debris (sphere, cube) as example, assuming that direction of the ablation reversal is the vertical direction of the micro surface and the impulse coupling coefficient of any area micro element is the same as that under the point radiation, we deduce the area matrix method from integral viewpoint. We obtain the influence rule of spot size and laser incident angle on the value and direction of impulse based on the area matrix method when the laser energy density or incident laser energy is given. These theoretical research results further enrich the theoretical study of laser cleaning space debris, and provide theoretical guidance for the scheme of laser cleaning space debris.