This study designs a wave energy classification scheme that comprehensively considers energy, environmental risk and cost factors. Furthermore, by rationally adjusting, adding or deleting the weights of related parameters, a dynamic self-adjusting energy classification under different requirements is proposed to satisfy different wave energy projects or equipments. A global ocean wave energy classification is performed as a case study. According to the results, the global wave energy classes are generally optimistic, and most of the global ocean is energy-rich. The regional differences in the wave energy classes obtained by the new scheme are obvious compared to those obtained by the traditional scheme. Significant differences in the wave energy classification results are observed under different requirements. The extents of energy-poor areas in the global ocean are the smallest when focusing on cost factors and the largest when focusing on resource output. The extents of energy-rich regions above class 6 are the widest when focusing on self-sufficiency and the smallest when considering cost factors. Regardless of the demand, the energy classes in the Southern Hemisphere are always higher than those in the Northern Hemisphere, and those in the eastern ocean regions are always higher than those in the western parts.