The invention relates to a device and a method applied to high-shearing-strength electromagnetic stirring treatment of melts and belongs to the technical field of metal materials and processing and molding thereof. The device mainly comprises a crucible, a core rod mounted in the crucible and an electromagnetic stirring device mounted at the periphery of the crucible, wherein the electromagnetic stirring device comprises a water tank and electromagnetic stirrers placed in the water tank; the shape of the crucible is semi-cone-shaped; the upper end of the core rod is a semi-cone-shaped structure; the lower end of the core rod is a helical structure; the middle part of the core rod is a hollow structure; the shape of the hollow part is a semi-cone-shaped; the core rod is coaxial with the crucible. The device and the method can be used for treating alloy melts such as aluminum alloys, magnesium alloys, copper alloys, zinc alloys and titanium alloys and the like and particle-reinforced metal-matrix composite materials. The metal melts treated by the method and the device are extremely uniform in temperature field and component field; molding blanks and parts are fine and uniform in structure and uniform in component distribution; the cast defects are greatly reduced; the performance is greatly improved; meanwhile, the production efficiency of the products is improved; the cost of the products can be greatly reduced.