An improved isocaudamer tandem repeat strategy for the production of short functional peptide was demonstrated in the study. The coding sequence of short peptide was codon optimized, and two isocaudamers were induced into the end of coding sequence. By re-cutting with isocaudamers and re-ligating, the coding sequence of short peptide in the expression vector was increased in a multiple manner (21, 22, 23, 24, 25 …….). In the present study, an 8 amino-acidresidue peptide of porcine reproductive and respiratory syndrome virus (PRRSV) was effectively expressed in 8 copies and 16 copies by this approach, then the proteins in 8 copies and 16 copies were used to generate antibody against this epitope in rabbits. The results showed that PRRSVs were well recognized by the antibody in indirect immunofluorescence assay. The technology using isocaudamer to insert multiple tandem repeats in the vector provides an important approach for the studies of small molecule peptides.