Inspired by the surface structure of Morpho butterfly wings, we theoretically propose a biomimetic nanosphere structure with high optical reflectivity. By adjusting the geometric parameters and material parameters of the nanostructure, we obtain reflectivity >99 % in a certain band; the high-reflection bandwidth depends on the period width, filling factor, and number of nanospheres. Its high-reflectivity bandwidth is less dependent on the incidental light angle compared with general single-layer or multilayer coatings for reflection enhancement. Unlike the biomimetic structures that are completely the same as the Morpho butterfly surface, this simplified structure can be assembled in ways other than photolithography and electron-beam lithography. We also analyzed several deviations of the structure, and the results show that our design allowed these deviations, which is helpful to achieving the effect of the structure in the preparation process. At the same time, the equivalent medium theory was used to analyze the nanostructure. The nanosphere structure has excellent potential applications in optical devices that require high reflectivity, such as laser resonant cavity and optical filters.