In this research, a method of magnetic enrichment of PCR amplification was built. First, target sequence was combined with biotin-modified specific primer and enriched to the surface of γ-Fe2O3. Then single target sequence was gained through degeneration, and performed PCR amplification. Simultaneously, the experiment conditions were optimized, such as the optimal hybridization temperature of target sequence and specific primers and the dosage of magnetic nanoparticles γ-Fe2O3. Besides, the sensitivity of the method was detected. Through the experiment, the optimum temperature of hybridization was 53℃, the optimum dosage of magnetic nanoparticles γ-Fe2O3 was 90μg, and the lowest concentration of target sequence could be detected was 5×10-7 ng/mL.