Abstract: The joining of FeCrAl alloy and carbon fiber reinforced thermoplastic composites (CFRTP) presents a promising strategy for lightweight aerospace component development. In this study, ultrasonic welding technology was employed to lap weld laser textured FeCrAl alloy and short carbon fiber reinforced polyamide 6 (SCFR-PA6). The cross-sectional morphology characteristics and joint bonding strength of the joint under ultrasonic loading processes in parallel and vertical directions were compared. The influence of ultrasonic vibration direction and laser etching asymmetric texture characteristics on the joint formation process and interface bonding mechanism is discussed. By evaluating the wettability of molten short carbon fiber reinforced polyamide 6 (SCFR-PA6) on laser-textured surfaces in different orientations, and combining microscopic characterization with interfacial mechanical property testing techniques, a comprehensive analysis was conducted on the cross-sectional morphology of joints and the characteristics of tensile-shear fracture surfaces. The results show that continuous groove structures promote resin flow. When the ultrasonic vibration direction is vertical to the tensile direction, a tightly bonded interface is formed. In contrast, when the vibration direction is parallel to the tensile direction, the molten SCFR-PA6 demonstrates good wettability and spreads readily, leading to significant resin loss, incomplete filling, and a loosely packed resin structure in the grooves, ultimately reducing joint strength. Furthermore, local metallurgical bonding at the interface was confirmed by EDS and XRD analyses. The synergistic regulation of "texture structure and ultrasonic vibration direction" is revealed, and the strengthening mechanism of the wetting and spreading behavior of molten resin and the enhancing bonding of heterogeneous interfaces during ultrasonic welding is elucidated.