Hyper-velocity kinetic impacts, penetration detonations, and similar methods are important means to alter the established orbits of potentially threatening asteroids, and they are also hot topics of research both domestically and internationally. Using multi-spacecraft formation technology can achieve the cumulative effects of kinetic impacts and penetrative detonation, resulting in greater orbital deflection. Multi-spacecraft formations not only need to ensure accurate impacts on asteroid targets but also must maintain a specific formation configuration during flight. To address the formation control requirements, a formation-keeping guidance method has been designed. Mathematical simulation results indicate that this method, while ensuring the target hit, meets the requirements for the cooperative formation configuration and the orientation of the formation plane normal during flight, demonstrating significant engineering application value.