<p>As the application of pure titanium materials in the field of precision machining becomes increasingly widespread, the study of the complex changes in internal microstructures and influencing factors during microforming processes has become increasingly significant. This study conducted heat treatments at different temperatures on pure titanium materials to obtain samples with varying grain sizes and microstructures. XRD examination of heat-treated pure titanium foils revealed that the β-phase was produced at temperatures below the theoretical allotriomorphic transformation temperature. Multiple micro-tensile tests were performed on annealed pure titanium. Microstamping technology was used to produce microstamped parts from pure titanium. By analyzing the stress-strain curves and standard deviation curves of mechanical properties, it was found that grain size and β phase significantly impact the stability of mechanical properties. Mechanical properties of pure titanium foil become progressively unstable with increasing grain size and β-phase content. Microstructural observations of the microstamped parts, combined with computer image processing techniques for quantitative detection of β-phase, revealed that under the influence of the size effect, the content of β-phase has a substantial impact on the microstamping forming results. The more β-phase content, the more difficult microstamping forming, the more concentrated β-phase distribution, the more likely to produce defects.</p>