To understand the differences in lactic acid and ethyl lactate isomer concentrations across baijiu of different aroma types, a method to directly measure them in baijiu was established, and their concentration patterns analyzed. Results showed that lactic acid enantiomers had a linear relationship within the range of 0.02~0.6 g•L−1, whereas ethyl lactate enantiomers exhibited a linear relationship within the range of 0.01~2.5 g•L−1. Significant differences were observed in the optical purity of lactic acid and ethyl lactate in baijiu of different aroma types. The contents of d- and l-lactic acid were relatively high in sauce-aroma type baijiu, with average mass concentrations of 1.348 g•L−1 and 0.440 g•L−1, respectively. The average mass concentrations of d- and l-lactic acid in strong-aroma type baijiu were 0.402 g•L−1 and 0.244 g•L−1, respectively, and those in light-aroma type baijiu were 0.161 g•L−1 and 0.042 g•L−1, respectively. In sauce-aroma type baijiu, the contents of d- and l-ethyl lactate were relatively high, with average mass concentrations of 1.280 g•L−1 and 0.283 g•L−1, respectively. The average mass concentrations of d- and l-ethyl lactate in strong-aroma type baijiu were 0.592 g•L−1 and 0.352 g•L−1, respectively, and those in light-aroma type baijiu were 0.211 g•L−1 and 0.038 g•L−1, respectively. In conclusion, the method developed in this study is easy to operate, exhibiting high precision and accuracy, and it is suitable for determining the optical activity of lactic acid and ethyl lactate in baijiu. The study findings clarify differences in the optical purity of lactic acid and ethyl lactate in baijiu of different aroma types, providing a foundation for further understanding the contribution of these compounds to the aroma profile of baijiu.