We constructed the first microsatellite-enriched library of the oriental armyworm (Pseudaletia separata) according to the strong affinity between biotin and streptavidin. Briefly, the approach involved adaptation of 300-700bp enzyme-digested fragments to adaptors, affinity capture of microsatellite repeat using biotinylated oligo-nucleotide probes ((CA)1, (GA)1, (GTT)12, (GAT)12, (TAGA)8, (GTGA)8) attached to streptavidin-coated magnetic beads, PCR amplification of captured moleculars using 21-mer primers complementary to the adapters, ligation of PCR products into pGEM-T, transformation of recombinant plasmids from each of the six preparations into DH5α competent cells. The sequencing results of 16 random samplings showed that 30.07% of the clones contained microsatellite sequences, more than 40% for CA, GTT and CAT libraries, a maximum of 56% among 16 samplings. High polymorphic single-copy microsatellite loci will be detected from six libraries. A large number of such loci are crucial to investigate ecological genetics, linkage mapping, molecular evolution and phylogeny et al. of oriental armyworm and will contribute to molecular ecology of insect migration.