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 . <EOS>