In order to detect the blast cells from bone marrow of patients, one strategy is to first isolate the cells using immunomagnetic beads. The aim of this study was to report the experimental results of the immunomagnetic separation efficiency of the blast cells from bone marrow of pediatric leukemia patients. To test the efficiency of immunomagnetic separation, flow cytometry measurements at critical steps were performed. We here reported 94.5% capture efficiency for CD10 nano beads. Patients samples were also analyzed with a microfluidic chip to test the feasibility for further developments.