Sodium salt is critical for determining the quality of fermented vegetables, with particular influence on their physicochemical properties, textural characteristics, and food safety. However, the relatively high salt levels in traditional fermented products do not align with the growing consumer preference for low-salt, health-oriented foods. Simply reducing salt levels compromises the storage stability, edibility, and processability of fermented vegetables. Therefore, lowering salt content while maintaining product quality poses a significant challenge for the fermented vegetable industry. Effective quality control in low-salt fermented vegetable production requires a comprehensive understanding of the role salt plays in product quality. In this review, we outline the functions of salt in fermented vegetables and detail the current applications and technological developments in salt-reduction strategies; we focus on sodium substitutes, biological salt-reduction approaches, and emerging non-thermal technologies. The current challenges in low-salt fermentation processes are also discussed, providing valuable theoretical and practical guidance for the high-quality processing of low-salt fermented vegetable products.