Objective To establish a quick, exact and inexpensive method to detect caries susceptibility in children. Methods 125 caries free children, aged 3-4 years, were randomly sampled. A combination of polymerase chain reaction（PCR） and gtfB oligonucleotide probe hybridization method was used to detect Streptococcus mutans in saliva. The participants were followed up for a year and the clinical examination results were compared with the laboratory results. The perspective study was used to evaluate the detecting approach. Results When the combination of PCR and hybridization method was used to detect caries susceptibility of the sample, the predictive sensitivity, predictive specificity and predictive reliability were all increased to 69.2%, 46.8% and 54.3%, respectively as compared to only PCR, which were 56.4%, 44.2% and 48.3%, respectively. The samples with both the positive and negative results of hybridization detection had caries clinically, but the dmft index and prevalence were higher in the positive（dmft was 2.15±0.86, and the prevalence was 23.28%） than in the negative（dmft was 1.58±0.51, and the prevalence was 10.34%） which was statistically significant（P
