A surface plasmon interference lithography method with a surface relief metal grating is proposed. The interference of the surface plasmon waves produced by a surface relief metal grating with a large feature size at the interface between the surface relief metal grating and a photoresist layer is studied by the finite element method. Numerical results show that the minimum feature size of interference patterns produced by a surface relief AI grating with the minimum feature size of 225.2 nm is smaller than 29 nm under the condition of 248 nm light illumination. Furthermore, the influence of some grating parameters on the intensity of the electric field of surface plasmon interference patterns has been discussed. It is found that the intensity of the electric field of surface plasmon interference patterns obtains its maximum when the groove width of the surface relief metal grating is about an integer multiple of the wavelength of the surface plasmon waves, which can be applied to optimizing the parameter of the surface relief Al grating.