Abstract: In order to obtain D,L-lactide with higher content of L-lactide, the optimum conditions for the synthesis of D,L-lactide by vacuum distillation were studied. Investigating and studying the catalyst selection and dosage, reaction time, reaction temperature and other processes, the optimal process conditions for lactide were determined. Polymerization was carried out under optimized reaction conditions, obtaining a long strip of D,L-lactide crystals with a crystal length of about 5~10 μm. The content of L-lactide in the mixture can be up to 76.5%.