PH is a key culture parameter for growth of Streptococcus suis and formation of lactate, and an appropriate pH is important to increase the cell d. of S. suis. Here, we investigated the effect of pH on S. suis fermentation, and the results indicated that the optimum pH range was 7.0-7.5 and pH controlled using a two-stage strategy [pH 7.0 (0-4 h) and pH 7.5 (4-10 h)] had a pos. impact on improvement of cell d. Specifically, NaOH was used to adjust pH during the initial 4 h and mixture of NaOH and KOH (2:1, volume/volume) were used to control pH during 4-10 h, which resulted in the concentrations of Na+ and K+ below the threshold for inhibiting S. suis fermentation Furthermore, a pH feedback feeding strategy was applied in S. suis fermentation, the concentration of residual glucose was maintained at approx. 0.10 g/L, and the accumulation of lactate decreased to 4.17 g/L, and the concentration of Na+ and K+ were 70.2 mmol/L and 30.1 mmol/L. which was accompanied by a high cell d. (2.347) and viability (8.42 × 109 colony forming units/mL) because of the reduction of lactate accumulation and proper levels of pH, Na+ and K+.