Using sodium alginate hydrogel as skeleton, in combination with chitosan and magnetic Fe₃O₄, a new type of magnetic chitosan/sodium alginate gel bead was prepared. On this basis, through the orthogonal experiment and single-factor experiment, the authors optimized the preparation conditions for composite gel bead, and determined the optimum one. The influences of many preparation impact factors on adsorption performance were examined. Results show that the optimal preparation conditions for the composite gel bead is as follows. Concentration of calcium chloride is 2.5 g/L, concentration of sodium alginate is 24 g/L, the amount of chitosan addition is 5 g/L, and the amount of magnetic liquid addition is 4.64 g/L. The optimal gel bead is a smooth, uniform, black ball with about 2 mm in diameter. By Fourier transform infrared spectroscopy (FTIR), synchronous thermal analysis (TGA) and other means of characterization, the adsorption mechanism is analyzed. Thermogravimetric analysis results show that the gel bead has good thermal stability. FTIR results prove that many active functional groups (amino group, hydroxyl group and carboxyl group) exist on the surface of gel bead. The adsorption performance test shows that adsorption ratio of 20mg MCSB on 40mL 25mg/L Cu²⁺ solution is 78.13%. The magnetic chitosan/sodium alginate gel bead is a novel simple-prepared and effective composite adsorbent.