D-alanine is a chiral molecule of L-alanine that participates in the formation and regulation of cell wall peptidoglycans, phosphoteichoic acid, spore germination and respiratory metabolism in individual bacteria. D-alanine participates in the formation and regulation of biofilm in bacterial communities. The function and metabolism of D-alanine in bacteria are specific, and the enzymes and genes in its metabolic pathway can be used as drug targeting sites. In this paper, the synthesis, metabolism and function of D-alanine in bacteria were reviewed, and the relationship between D-alanine and pathogenicity of Streptococcus mutans was discussed to provide a theoretical basis for candidate targeting sites of anti-caries drugs. According to existing research results, the enzymes and related genes involved in D-alanine metabolism play important roles in the growth and biofilm formation of Streptococcus mutans, and D-alanine is expected to be a target for the design of anti-caries drugs.