In this study, the method established in paper 1 was used to analyze PABA synthesized by S. sanguis S34. The results showed: 1. S. sanguis S34 did synthesize PABA and the mean concentration of PABA was 1.236 micrograms/ml. 2. the components had good linear relation and average recovery was 80%. The results of this paper will be helpful to studying influencing factors on PABA synthesis of S. sanguis and the roles of PABA in microbial homeostasis of dental plaque.