A detailed theoretical derivation and calculation method of the difference coefficient between a light distribution pattern of a 30×20µm2 green micro-LED array and Lambert source is proposed first in this paper, to the best of our knowledge, which establishes an accurate relationship between external quantum efficiency and current efficiency (cd/A). The variation of capacitance with voltage and wavelength blueshift is illustrated by a carrier recombination mechanism. The current efficiency reaches 132.5 cd/A for the 60×50µm2 and 121.7 cd/A for the 25×15µm2 arrays, and the mechanism caused by size dependence is analyzed in detail combined with the classical ABC model.