Abstract： Objective To analyze the community in dental plaque of elder people with root caries.Methods Total DNAs were extracted from the root caries dental plaques of nine elders over 60 years of age.Polymerase chaid reaction-based denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the microbial composition,DGGE bands were excised from the gels for sequencing and identification.Results The dominant genus in root caries dental plaque of elder people were:Acinetobacte [0.9％ (1/114) ],Actinobaculum [ 1.8％ ( 2/114 ) ],Actinomyces [ 15.8％ ( 18/114 ) ],Aggregatibacter [0.9％ (1/114) ],Capnocytophaga [ 14.0％ ( 16/114 ) ],Corynebacterium [ 0.9％ ( 1/114 ) ],Haemophilus [0.9％ ( 1/1 14 ) ],Mobiluncus [ 0.9％ ( 1/114 ) ],Naxibacter [ 0.9％ ( 1/1 14 ) ],Neisseriaceae [ 10.5％ (12/114) ],Porphyromonas [ 0.9％ ( 1/114 ) ],Prevotella [ 12.3％ ( 14/114 ) ],Selenomonas [ 6.1％(7/114 ) ],Staphylococcus [ 1.8％ ( 2/114 ) ],Oralis streptococcus [ 6.1％ ( 7/114 ) ],Mutans streptococcu [7.9％ (9/114) ],Tannerella [0.9％ ( 1/114)],Treponema [ 1.8％ (2/114)],Veillonella [ 10.5％(12/114) ] and two uncultured unknown genus [ 1.8％ (2/114 )].Uncultred genotypes accounted for 19.30％ of the total.Gram-positive bacteria genotype accounted for 31.6％ (36/114),and Gram-negative bacteria genotype accounted for 66.7％ (76/114).Conclusions There were many bacteria genotypes in root caries dental plaque in the elderly,which were widely distributed.Gram-negative bacteria accounted for the majority.Genotype-specific pathogenic bacteria were not found.