Diffractive waveguide is a mainstream technical solution to realize augmented reality near-to-eye display, which has the advantages of a large eye-box, light volume, and good mass production. However, unified definitions for the evaluation indexes of some key parameters of diffractive waveguides are still lacking. This work provides a detailed introduction to diffractive waveguide scheme main parameters and measurement methods. The advantages and disadvantages of diffractive waveguides are investigated by clarifying key parameters to maximize their technical potential and improve product performances.