The impulse coupling characteristics of space debris irradiated by pulsed laser with big spot was studied. The impulse coupling characteristics of planar debris under big and small spot irradiation were studied conservatively. The influence rules of shape and spot size under big spot irradiation on impulse coupling characteristics were studied. The rationality of theoretical research was verified by the experimental results. The results demonstrate that the impulse coupling coefficient with big spot radiation is higher than that of small spot radiation under the same laser power density. Impulse coupling coefficient under big spot irradiation is mainly affected by laser power density. The influence of spot size on impulse coupling coefficient is small. The theoretical calculation results of impulse coupling coefficient under big spot irradiation are closer to the experimental results. The above experimental results have certain guiding significance for the theoretical study of laser irradiated non-planar space debris.