<p>Metal bipolar plates are critical components in high-performance fuel cells. However, when fabricating ultra-thin-wall microchannel structures using the roll forming process, issues such as cracking and distortion frequently occur, which limit the enhancement of the reaction performance and service life of metal bipolar plates. This study proposes a novel soft mold roll forming process for ultra-thin-wall microchannel structures. A dedicated soft mold roll forming apparatus was developed, comprising roller modules, pressure modules, and intelligent control modules. Based on this, the effects of roller structural features and soft mold properties on the deformation behavior of microchannel structures were investigated. The results indicate that the soft mold roll forming process enables tensile deformation along the entire profile of the microchannel structures, thereby reducing the risk of cracking and weakening the size effect. The greater the roller pressure, the thinner the soft mold thickness, and the larger the groove depth and fillet radius, the stronger the bulging capability of the soft mold, resulting in a higher depth-to-width ratio of the formed microchannel structure. When the groove spacing-to-width ratio is less than 0.5, the foil within the groove interval enters a material-starved state, and excessively small groove spacing results in severe thinning of the microchannel structures. A critical soft mold hardness value, Shore A50, was identified, at which the depth-to-width ratio of the formed microchannel structures reaches its maximum. Finally, optimized process parameters were selected to fabricate microchannel structures with uniform geometry, high distribution density, large depth-to-width ratio, and uniform thickness distribution. These findings provide methodological guidance for eliminating forming defects in microchannel structures and improving the forming quality of bipolar plates.</p>