Abstract: The 24Mn3Al4/53Mn5Al4 dual lightweight steel composite was fabricated through sequential electroslag remelting, employing a graded strategy where the higher-density 24Mn3Al4 steel (approximately 7.16 g/cm³) was first remelted followed by the lower-density 53Mn5Al4 steel (approximately 6.92 g/cm³).The effect of electrode melting rate (0.000 5–0.001 5 m/s) on the interfacial morphology and bonding strength was investigated through finite element simulation and experimental verification.The results show that during continuous remelting, the system temperature is characterized by a distribution pattern of slag pool (highest) → metal molten pool → mold (lowest). Both the temperature field and the molten pool morphology are observed to exhibit an axisymmetric U-shaped structure with significant temporal stability. When the melting rate is increased from 0.0005 m/s to 0.0015 m/s, the molten pool depth shows significant enhancement (the H_M/D_In increases from 0.29 to 0.65) accompanied by expansion of the high-temperature zone at the slag/metal interface and widening of the mushy zone. At the intermediate melting rate of 0.0010 m/s, the optimal interfacial bonding strength of 574.89 MPa is achieved, representing 49.7% and 12.2% improvements compared to the values obtained at 0.0005 m/s (384.08 MPa) and 0.0015 m/s (512.61 MPa) respectively, indicating this melting rate parameter is optimal for fabricating the double lightweight steel composite. The simulation and experimental results show a high degree of agreement (H_M/D_In error <10%), which effectively verifies the reliability of the finite element model. This study provides a theoretical basis for the optimization of the preparation process of lightweight steel composites.