Abstract: In order to study the erosion morphology of polyimide (PI) film materials under atomic oxygen (AO) attack in low Earth orbit (LEO), a method based on the intersection simulation of local grid boundaries was proposed. The periodic boundary method was applied to obtain the surface morphology. The difference between the calculation results of the erosion morphology and those of the experimental results in the literature was less than 4%, which proved that the interactions between AO and PI materials simulated by the proposed method was close to the experimental results. Using the arithmetic mean deviation and standard deviation of erosion depth as the morphology description, it was found that these two parameters all increased by power 0.253 with the increase of AO fluence. The ratio of standard deviation to arithmetic mean deviation remained basically unchanged with the increase of AO fluence, indicating that the surface morphology remained basically unchanged under the AO attack, when only the height of peaks and the depth of valleys increased. In addition, there was little difference in the surface erosion morphology of PI under different orbital velocities. The above results help to further understand the formation mechanism of PI surface erosion morphology under AO attack.