The EMuS is an excellent platform for the R&D of the key technologies of the next-generation neutrino beam facility at CSNS (China Spallation Neutron Source), also for the multi-disciplinary applications based on μSR technique. The dipole on the EMuS beamline used for minus/positive particle selection and deflection is designed as a superferric magnet in detail because of its large aperture and high field. The 2D and 3D magnetic field simulations are described. Some optimal methods are employed to reach the required field homogeneity which is better than ±5.0E-4 at 1.5 T in a wide aperture of 320 mm×320 mm. The yield stress and stain analysis of coils show that the magnetic and mechanical designs of this magnet is better than the expected requirements.