The radially polarized light can be tightly focused and then forms a strong longitudinal electric field. The longitudinal electric field which follows the form of zero order Bessel function in cross section is calculated based on the Kirchhoff diffraction theory when radially polarized light is reflected and focused by a conical mirror. The relationships among spot size of incident light, cone-apex angle, radius of the exit end of conical mirror and coherent length and lateral width of the optical field of convergence region are analyzed. With these results, a hybrid structure consisting of a conical mirror and a cylindrical reflection mirror is proposed. When the appropriate parameters of conical mirror and the cylindrical reflection mirror are designed, the cascaded and periodic distribution longitudinal electric field is formed, and then the dependence of the related parameters (including lateral width, period and duty circle) of cascaded longitudinal electric field on parameters of cylindrical reflection mirror is discussed. Results show that a cascaded longitudinal electric field with periodic length of 1154λ and duty circle of 1 is formed when the conical mirror has an cone-apex angle of 60° and the radius of the exit end and the inner diameter of cylindrical reflection mirror are both 999.682λ (λ is the wavelength). This simulation suggests that the acceleration zone length can even reach the meter level when it is used for electronic acceleration. The design of this cascaded longitudinal electric field will further increase the length of the electron acceleration region to a significant extent, which could accelerate the electronics to higher energy.