This study focuses on the influence of sheet thickness and other process parameters on the formability of SUS304 stainless steel sheet formed by MSPIF technology. In the paper, SUS 304 sheet with 2 thicknesses of 0.4 mm and 0.5 mm were selected in order to find out the real influence of the sheet thickness on the formability. The application of Taguchi experimental design method with an L9 orthogonal array, 4 process parameters target forming angle Δα, step down increment Δz, pestle diameter D and pestle feed speed Vxy were examined to evaluate their influence on the formable angle α at various positions along the forming depth. Analysis of variance (ANOVA) indicates that the step angle Δα and step-down increment (Δz) are the most influential factors affecting the achieved wall angle α. These findings offer a basis for selecting suitable sheet thickness and process parameters to optimize forming performance by MSPIF process.