We proposed a plasmonic lens (PL) to achieve far-field focusing performance under a 532 nm wavelength. This lens is produced by perforating multiple concentric rings on the gold layer, and the radius and width of the ring can be designed flexibly. Its machining process has adopted the electron beam lithography and lift-off technology. The lenses are designed within a small range of phase delay and the small-sized slits of the PL are replaced with a larger-sized one, which has almost no impact on either the full width at half maximum (FWHM) or the focal length of the PL. With an increase of the slits width, a further enhancement of the spot intensity has been observed. Meanwhile, both the numerical relationships of simulation and experiment are consistent. This method can reduce the difficulty of PL processing, by which the PL with large-sized slits has almost the same performance as that of small-sized ones. The method is of great significance to the low-cost production of modern optoelectronic devices, and it would promote potential applications in optical interconnection devices, controllable focusing, and superresolution imaging.