Abstract: Aiming at the problem of rapid simulation of SAR electromagnetic imaging of complex group targets, a K-d tree construction based on breadth-first search (BFS) algorithm is used, which significantly improves the time-domain shooting and bouncing ray method (TDSBR) ray tracing efficiency. The time-domain shooting and bouncing ray method is used to analyze the time-domain electromagnetic response characteristics of complex electrically large-size targets. The radar echo signal is focused by combining the back-projection (BP) algorithm to obtain a high-resolution synthetic aperture radar (SAR) image of the complex target. By comparing with the frequency domain ray tracing algorithm in FEKO software, the effectiveness of the proposed TDSBR algorithm in analyzing the electromagnetic scattering characteristics of complex group targets is verified. The imaging results show that TDSBR combined with the BP algorithm can effectively handle the SAR electromagnetic imaging simulation problem of complex group targets.