To address the issues of agglomeration during magnetic particle capture and the incomplete release of these particles during reuse in microfluidic chips for library preparation, a microchamber was utilized to enhance the dispersion area for magnetic particle capture. Additionally, the release of magnetic particles was achieved through the synergistic action of flow field and magnetic field. The simulation results indicated that as the inlet flow velocity varied from 0.02 m/s to 0.16 m/s and the magnet spacing ranged from 1.2 mm to 1.8 mm, the coverage of magnetic particles in the microchamber increased from 17.29% to 63.59%. Meanwhile, the magnetic particle capture rate decreased from 100% to 35.2%. These processes were further validated through experimental methods. During the release process, the trajectory of magnetic particles under the synergistic effect of flow field and magnetic field aligned with expectations. The captured magnetic particles were released from the microchamber within 12 s, achieving a release rate of 100%.