A physical phenomenon has been found: in a structure of nanometal film with dielectric-medium loading, the surface polaritons excited by a uniformly moving electron bunch can be transformed into Cherenkov radiation with intensity enhancement in the medium. Based on this mechanism, the surface polariton Cherenkov light radiation source is presented and explored in the Letter. The results show that surface polariton Cherenkov light radiation source can generate radiation, from visible light to the ultraviolet frequency regime and the radiation power density can reach or even exceed 10(8) W/cm(2) depending on the beam energy and current density. It is a tunable and miniature light radiation source promising to be integrated on a chip and built into a light radiation source array.