When the electron plasma is blown from the solar wind and enters into the earth atmosphere, a large number of neutral particles are excited to cause the significant event called aurora phenomenon. In this process, there are several sources of excitation including electron impact, dissociative recombination, thermal electron excitation. Particularly, auroral optical radiation produced by electron impact on oxygen atoms is investigated to explore the relationship between secondary electron energy and spectroscopic emission features. Based on the ground observations of aurora spectral images, the emission characteristics reveal the primary electron energy and flux, the basic atmosphere of species concentration and electron temperature, abundant information of the deposited particles. With the consideration that the radiations of atomic oxygen 5577 Å and 6300 Å are representative auroral spectral lines, we use numerical calculations of relative intensity ratio I(λ5577)/I(λ6300) for various energies to approximate the true ratio. A theoretical primary energy is then determined and used to estimate radiation features at other spectral bands. The best approximated primary characteristic energy is determined as 0.585. The estimated pixel lines of λ6300 and λ6364 underestimate with a factor ranging from 0.95 to 2.2 and from 0.92 to 1.41, respectively.