Abstract: Measurements and analysis with SEM, EDS, XRD confirmed that the intermetallic compounds in aluminum/steel MIG-brazed interface consisted of Fe₂Al₅ and FeAl₃ phases. Based on Monte Carlo method, the diffusion of Al and Fe in aluminum/steel interface and growth model for Al-Fe intermetallic compounds were established, and numerical analysis and comparative study were conducted. The results show that the proposed model could well reflect the growth of Fe₂Al₅ phase on steel side, and FeAl₃ discretely existed on aluminum side, and the thickness of the intermetallic compound was close to the experimentally measured results.