Multi-beam broadband phased array seeker can search, track, guide and identify stealth cluster targets efficiently. Its application in weapons requires hardware-in-loop simulation to construct complex combat scenarios of group targets or target/jamming coupling. Affected by the coupling effect, the modeling of group targets requires a lot of computing resources and time. This paper proposes a real-time simulation method for group targets based on multiple scattering centers. Through structural analysis, the complex structure of the target is classified and partitioned, and the independent and clear electromagnetic scattering contributions of each part are obtained. As the results, multiple scattering centers are quickly extracted and group targets are efficiently modeled. Meanwhile, the coupling effect between the target and the environment is modeled to improve the efficiency and fidelity of group target combat scenarios. Taking a typical combat scenario as an example, the simulation results show that this method improves the computational efficiency by more than 6,00 times compared with the traditional algorithm, and can quickly complete the modeling of group targets such as aircraft formations and missile clusters. The high-confidence combat scenario constructed by this method can be applied to the hardware-in-loop simulation experiments of multi-beam broadband phased array seeker, laying a solid foundation for the successful design, development and verification of the weapons.