Abstract: Lactococcus lactis, a well-characterized probiotic bacterium with a simple metabolic network and "Generally Recognized as Safe" status, has emerged as a promising chassis in synthetic biology with broad industrial applications. This review provides a comprehensive overview of recent advances in synthetic biology tools developed for L. lactis, focusing on the construction and application of genome-scale metabolic models, gene expression systems, and genome-editing technologies. Through the precise modulation of metabolic pathways, researchers have accelerated the transition of L. lactis from a traditional fermentation strain to an intelligent microbial cell factory, facilitating its use in the development of functional foods, targeted drug delivery systems, and the sustainable production of bio-based chemicals. Future efforts should aim to integrate machine learning-driven multi-omics modeling with dynamic regulatory networks to achieve more precise metabolic design and scalable industrial deployment.