In order to clarify to what extent the PVDF fiber is stretched during the spinneret stretching stage in the actual production process and then post-stretched ( the distribution of the spin-stretching ratio and the poststretching ratio in the total stretching ratio, that is, the tensile ratio combination), the manuscript aims to explore the influence of different tensile ratio combination on the crystal structure of PVDF fibers. In the study, PVDF fibers with different spin-stretching ratios were prepared by melt spinning, and further PVDF fibers with different post-stretching ratios were fabricated through post-stretching treatment. The crystal structure and properties of the fibers were analyzed by characterization techniques such as Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry ( DSC). The results indicate that increasing the spin-stretching ratio can significantly improve the crystalline structure of PVDF fibers, enhancing their crystallinity from 41.3% to 57.4% . In contrast, the effects of post-stretching process is mainly reflected in the aspect of crystal form transformation. Increasing the post-stretching ratio can more effectively induce the transition from α crystal form to β crystal form, with the β crystal content rising from 40.2% to 75.3% . Meanwhile, the mechanical properties have also improved significantly, increasing from 85 MPa to 350 MPa. The spin-stretching process and post-stretching process exhibit a synergistic effect during the preparation of PVDF fibers. The former primarily regulates the crystallinity, while the latter dominates the crystal form optimization. The reasonable combination of the two can achieve precise regulation of the structure and properties of PVDF fibers.