Objective To recognize the possibility of Y fragment deletion of Amelogenin gene intuitively and simply according to the genotyping graphs.Methods By calculating the ratio of total peak height of genotyping graphs, the statistics of equilibrium distribution between Amelogenin and D3S1358loci,Amelo-genin X-gene and Amelogenin Y-gene, and different alleles of D3S1358loci from 1968 individuals was analyzed after amplified by PowerPlex? 21 detection kit.Results Sum of peak height of Amelogenin X allele was not less than 60% that of D3S1358loci alleles in 90.8% female samples, and sum of peak height of Amelogenin X allele was not higher than 70% that of D3S1358loci alleles in 94.9% male samples.Conclusion The result of genotyping after amplified by PowerPlex? 21 detection kit shows that the possibility of Y fragment deletion should be considered when only Amelogenin X-gene of Amelo-geninis detected and the peak height of AmelogeninX-gene is not higher than 70% of the total peak height of D3S1358loci.