Nanophotonic imaging technology is one of the primary methods in modern optical imaging and measurement systems. However, traditional broadband achromatic metalenses face issues such as increased structural complexity, reduced imaging efficiency, and lower focusing resolution with the addition of working wavelengths, which limit the development of high-performance, integrated miniature optical systems. Graphene oxide is a two-dimensional material with high refractive index and high transmittance. By using laser direct writing technology, specific areas of graphene oxide are thermally reduced to reduced graphene oxide, altering the optical properties of the material and enabling the fabrication of ultrathin planar lenses. Addressing the discrete wavelength dispersion issue of graphene oxide lenses, this paper proposes a reverse design method based on an improved genetic algorithm. By setting optimization goals for the genetic algorithm and incorporating a penalty factor into the objective function, the lens structure can be targeted for optimization, designing a graphene oxide lens capable of focusing discrete wavelengths into a single focal point with equal intensity. The designed graphene oxide lens (approximately 200 nm thick) was fabricated using vacuum filtration and femtosecond laser direct writing techniques, and its focusing characteristics were characterized. Experimental results show that this lens can excellently control dispersion for incident wavelengths of 450, 550, and 650 nm, with a maximum deviation from the preset focal length of only 2.23%. The average radial full-width at half-maximum (FWHM) of the lens′s focal points for working wavelengths is 324.3 nm, achieving sub-diffraction-limited focusing. This design method offers new possibilities for miniature optical systems that require high resolution and broad bandwidth dispersion control.