The present invention discloses a method of three-dimensional optimization design for an asymmetric cusp magnetic field in an MCZ single crystal furnace. An optimization design for structural parameters of the magnetic field comprises first establishing a three-dimensional magnetic model by using an Ansys numerical analysis software; and varying parameters of the model, determining the span between the upper and lower parts of coils, the number of transverse turns of coils and the thickness of the shield based on a set magnetic induction intensity of the magnetic field, and determining the numbers of longitudinal layers of coils in the upper and lower parts of the magnetic field. An optimization design for specification parameters of the coils of the magnetic field comprises first determining a relationship between heat and specification parameters of the coils, determining a relationship between heat transfer of the coils at the copper pipe walls and the specification parameters of the coils, analyzing the heat absorbed by cooling water, establishing an optimization model of a system, and optimizing the specification parameters of the coils of the magnetic field by using the Ansys software. According the method of the present invention, the influence of the structural variation of the magnetic field on the variation of distribution and intensity of the magnetic field is intuitively revealed in three-dimension in view of all aspects, thereby reducing develop period and experiment cost on the cusp magnetic field, and increasing the efficiency of generating magnetic induction intensity by the magnetic field.