Abstract: Two kinds of Cu-15Ni-8Sn alloy rods are prepared by vertical semi-continuous casting with and without magnetic field applied. The microstructures of the two alloy rods are observed, their grain sizes measured, their element distributions observed, and their mechanical properties tested. Results show that a small amount of dendrite structure is found in the microstructure of the sample without magnetic field, while the microstructure of the sample with magnetic field is composed of uniform and fine equiaxed crystal. The average grain size of the sample without magnetic field is 833.7 μm, and that of the sample with magnetic field is 54.6 μm. The microsegregation of Sn element in the sample with magnetic field is improved. Compared with the sample without magnetic field, the size of Sn-rich phase of the sample with magnetic field is smaller and the distribution is more uniform. The tensile strength, yield strength and percentage elongation after fracture of the sample with magnetic field are 465 MPa, 290 MPa and 15.4%, respectively. Those of the sample without magnetic field are 429 MPa, 242 MPa and 23.9%, respectively.