An electromagnetic lens, wherein the electromagnetic lens is a winded body made of a strip material, a dielectric material is distributed on a surface of and/or inside the strip material, and a dielectric constant of the dielectric material gradually changes in both a transverse direction and a longitudinal direction of the strip material; when the strip material is winded to be the winded body, the dielectric material is distributed in at least one artificially predetermined three-dimensional space range inside the winded body, and the three-dimensional space range with the dielectric material distributed is called a lens body; a part of the winded body besides the lens body is called a non-lens part; the dielectric constant of the lens body is not lower than the dielectric constant of the non-lens part of the winded body; the dielectric constant of the lens body gets lower and lower in all directions from inside to outside of the lens body, and each direction from inside to outside of the lens body indicates a direction from a central area of the lens body to a boundary of the lens body, wherein the lens body is divided into a number of dielectric constant step layers; a dielectric constant step layer having a higher dielectric constant value completely wraps a dielectric constant step layer having a lower dielectric constant value; respective dielectric constant values of adjacent dielectric constant step layers are stepped; and the dielectric constant of the lens body decreases in a step manner in a direction from inside to outside of the lens body, wherein if the strip material is unwinded, the dielectric material is distributed on a specific plane area of the strip material, such a specific plane area is called a dielectric distribution area; the dielectric distribution area is divided into a number of sub-distribution areas, and a sub-distribution area having a higher dielectric constant is half or fully surrounded by a sub-distribution area having a lower dielectric constant; when the strip material is winded from a sub-distribution area having a highest dielectric constant, each sub-distribution area corresponds to a dielectric constant step layer of the resulting lens body. wherein the lens body is divided into a number of dielectric constant step layers; a dielectric constant step layer having a higher dielectric constant value completely wraps a dielectric constant step layer having a lower dielectric constant value; respective dielectric constant values of adjacent dielectric constant step layers are stepped; and the dielectric constant of the lens body decreases in a step manner in a direction from inside to outside of the lens body, wherein if the strip material is unwinded, the dielectric material is distributed on a specific plane area of the strip material, such a specific plane area is called a dielectric distribution area; the dielectric distribution area is divided into a number of sub-distribution areas, and a sub-distribution area having a higher dielectric constant is half or fully surrounded by a sub-distribution area having a lower dielectric constant; when the strip material is winded from a sub-distribution area having a highest dielectric constant, each sub-distribution area corresponds to a dielectric constant step layer of the resulting lens body.