Combining the spectra of could-to-ground lightning discharge processes obtained by a slit-less spectrograph with the synchronous electrical information, the temperature, the linear charge density, the channels initial radius, the final radius and the energy per unit length are calculated. The results of these parameters are in agreement with the values reported in other work. The correlative analysis indicates that the arc initial radius mainly depends on the duration of the discharge current, the radius increases with temperature rising, and the total intensity of spectra is correlated positively with initial radius and energy per unit length. The energy per unit length is directly proportional to the square of initial radius.