Streptococcus mutans (S. mutans) is considered the primary bacteria responsible for dental caries, and specific recognition and fluorescence labeling can achieve accurate detection and early diagnosis of oral diseases such as dental caries. However, due to the weak stability of traditional imaging probes in solution and a lack of specific recognition functions, there are still significant challenges in fluorescent imaging detection of dental caries lesions. Herein, we report a peptide-QDs composite fluorescent probe that can achieve highperformance imaging of S. mutans and enable early diagnosis of the susceptible sites and hidden early carious lesions of dental caries. This fluorescent probe has high fluorescence stability, good biocompatibility, and low biotoxicity in physiological environments. It can specifically recognize and fluorescently label S. mutans, responsible for early dental caries, accurately locating dental lesion sites. Combined with visible fluorescence analysis, it is more convenient to screen for hidden dental lesions that might otherwise be ignored. Due to its low synthesis cost, stable storage, and simple imaging method, the peptide-QDs composite fluorescent probe can be widely used in routine dental examinations for accurate screening of dental diseases.