Lactic acid is an important biochemical product. With the global pollution caused by plastics, especially marine plastics, the demand for lactic acid to produce polylactic acid has rapidly increased. However, the high costs of raw materials and fermentation–separation processes have severely limited lactic acid production. In this study, the research trend on lactic acid fermentation in recent years was analyzed by a bibliometric survey, and the latest progress in lactic acid fermentation using different biomass stocks and microorganisms is summarized. The effects of different fermentation modes and fermentation–separation coupling methods on lactic acid fermentation were analyzed. Finally, microbial strains for cooperative fermentation and polysaccharide utilization are discussed. It is meaningful to develop environmentally friendly, cost-effective in situ product removal technologies, use lactic acid as an intermediate to higher value-added products, and co-produce lactic acid and other products based on a biorefinery model.