Abstract: Abstract: Objective In order to select microsatellite loci suitable for genetic detection of the outbred beagle dogs and to primarily adapt to analyze the genetic structure of one outbred population of small beagle dogs. Method We selected 120 microsatellite markers included with 23 loci from beagle dogs and 97 loci from other canine strains. The PCR conditions of these loci were optimized by DNA pool. The loci of better amplification effect were selected to analyze further with fluorescence labeled STR scanning and population genetic structure. Result A total of 73 loci were successfully amplified, within which 49 loci were used to calculate genetic information after STR scanning. It was shown that the small beagle dog population exhibited the effective number of allele 4. 9230, expected heterozygosity 0. 7574, average heterozygosity 0. 7375, Shannon ’ s information index 1. 6625 and PIC 0. 7038, respectively. It showed that the examined population exhibited high and abundant population genetic polymorphism information and high genetic diversity. Conclusion The set of 49 microsatellite loci we optimized could be adapted for genetically monitoring outbred beagle dogs. These loci are valuable to be verify and optimize using more populations.