The present paper covers a novel technology for the concentration of trace amounts of target oligonucleotide from the solution. This technique is based on a super-paramagnetic DNA nano-enricher constructed with a single strand DNA probe immobilized onto the surface of the super-paramagnetic nanoparticles prepared by using the water-in-oil microemulsion technique, employing silica as the shell and iron oxide as the core of the super-paramagnetic nanoparticles. The silica coated magnetic nanoparticles are (40±4) nm in size. And the magnetic nanoparticle is super-paramagnetic. Biotin labeled ssDNA(Biotin-5-(A)10-GAT-TCA-CGA-GGC-CCT-AGT-CG-3) was immobilized on the surface of silica coated magnetic nanoparticles. The complementary ssDNA could be enriched effectively and the characteristics of the enriched ssDNA have not changed, which will provide a novel technique and measurement for gene transfection, mutation detection, gene diagnosis, gene therapy and so on.