This paper focuses on the failure behavior of steel dual-angle with cruciform welding filler plates (DA-CWP) under compression. A total of three DA-CWP specimens were fabricated and tested under axial compression, where different slenderness ratios (i.e., 45, 60, 75) were considered for comparison. The failure performance was experimentally investigated from different perspectives, such as failure mode, ultimate capacity and strain development. Subsequently, numerical simulation was performed to further reveal the effect of slenderness ratio and filler plate type on the failure behavior of DA-CWP. Finally, A theoretical method to distinguish the compressive failure mode of DA-CWP was proposed, and the bending-torsion transition slenderness ratio calculated by theoretical method was compared with the one from simulation for verification. The results demonstrate that the failure mode of DA-CWP changes from torsion to bending as the slenderness ratio increases, gradually decreasing its ultimate capacity. Due to the lower torsion stiffness of steel dual-angle with alternate plates (DA-AP), the torsion instability is more prone to occur for DA-AP, resulting in larger deformations of DA-AP compared to DA-CWP under identical compression. The theoretical method proposed in this study provides a good prediction for the bending-torsion transition slenderness ratio of DA-CWP under axial compression, which can provide reference for ultimate capacity design.