STR is a universal genetic marker that has changeable polymorphism and stable heredity in human genome. It is a specific DNA segment composed of 2-7 base pairs as its core sequence, and is formed through the repeated connection of the same one. Since it has the characteristics such as numerous allelic genes, highly heterozygosity and easy recognition and short PCR segment, it is employed as an ideal DNA marker in such practical fields as human genetics and forensic medicine. In this study, we investigated the polymorphism of STR of Naci minority with STR genescan marked by fluorescence. Seventy-two alleles of 9 STR in Naci were detected with their frequency 0.0052-0.5208 and 165 genotypes were found out with frequency 0.0104-0.3021. Hi-Square test indicated the distribution of genotypes agreed with Hardy-Weinberg equilibrium (P > 0.05). Statistical analysis showed the followings: the heterozygosity (H) > 0.6 in each locus, the average polymorphism information content (PIC) > 0.7, Mean discrimination power (DP) > 0.8, probability of paternity exclusion (EPP) > 0.5, indicating that the STR markers used in the study were of great value in the researches of minority genetics. This not only founds the base for genetic structures of STR of Chinese but also provides valuable information for anthropology, forensic medicine and ethnology.