Titanium and aluminium are two metals that are frequently utilised in aerospace, pipeline, and vehicle manufacturing due to their distinct physical properties, which can result in undesirable outcomes such as intermetallic compounds and cracks at the welding interface when compared with welding single metal materials. To address this challenge, an ultrasonic assisted resistance spot welding technique was employed as a welding method, and the welding process parameters were meticulously optimised. The Box-Behnken experimental design, constituting a response surface method, was utilised to determine the optimal welding quality and evaluate the mechanical properties of the welded joint under the optimal welding conditions. The main process parameters (welding current, welding time, electrode pressure) were employed to ascertain the appropriate processing conditions for welding. The optimal processing conditions for the welding were identified as 10.5 kA welding current, 19 cycles welding time and 0.2 MPa electrode force. The process was applied to actual resistance spot welding production, and the weld was verified by tensile shear test.