<p>A novel superplastic forming process, driven by a supersonic fluidic oscillator to generate an oscillating gas pressure (SFO-SPF), was shown to significantly reduce the forming time compared to the conventional SPF of AA5083 aluminum parts. The strong interaction between solid and fluid mechanics brings challenges for reliably modelling such a unique process. This work focuses on a hybrid solid–fluid model that simulates both the solid and fluid mechanics involved in SFO-SPF. The metal forming is modelled by using finite element analysis (FEA) conducted using ANSYS LS-DYNA, with a decoupling approach to solve a stability issue related to the strain-softening characteristic of the material model. An equivalent fluid circuit with system dynamic theories is utilized to model the pressure changes caused by the applied supersonic fluidic oscillator. The pressure load acting on the solid material from the working fluid during the SFO-SPF process is determined by embedding the fluid and heat transfer simulations into the FEA to construct a looped system. The results are validated with experimental data collected from the SFO-SPF trials using AA5083 aluminum sheets. This solid–fluid hybrid model provides accurate estimations of the fluid pressurization in the forming chamber and accurate predictions of the final thickness distribution across a part made by the SFO-SPF process, and is shown to enable further studies of the performances of SFO-SPF.</p>