The invention relates to a polarization conversion method based on artificial electromagnetic materials. Electromagnetic waves are controlled to be spread in the artificial electromagnetic materials which constitute a polarization converter by designing the structure of the artificial electromagnetic materials, thereby leading the relation of the transmission coefficients of an electric field in the different directions to achieve the conversion from one incident wave polarization state to another emergent wave polarization state in a plane which is perpendicular to the wave spread direction, the relation of the transmission coefficients needs to be met is as follows: if the spread direction of the electromagnetic waves is defined as an X axis of a three-dimensional rectangular coordinate, the electric field E is decomposed to two electric field components of Ey and Ez which are mutually perpendicular, E is equal to yEy plus zEz, the transmission coefficients of T<y> and T<z> of the electric field in the two directions which pass the materials that constitute the polarization converter meet the following conditions: 1) for the situation of converting the incident waves with any polarization state to the emergent waves with the linear polarization, the absolute value of T<y>\the absolute value of T<z> is equal to p multiplied by the absolute value of Ez\the absolute value of Ey; ang(T<y>) minus ang(T<z>) is equal to plus or minus n pai minus (ang(Ey) minus ang(Ez)); wherein, n is equal to 0, 1, 2,..., p is the tangent value of an included angle theta between the linear polarization direction of the emergent waves and a z axis, p is not less than 0 and not more than 1, ang(T<y>) and ang(T<z>) represent the relative phases of T<y> and T<z>, ang(Ey) and ang(Ez) represent the relative phases of Ey and Ez. The polarization conversion method has the advantages of low cost, low energy consumption, high efficiency and compact structure.