In this paper, we report the first observation of continuum emission band of 225～235 nm with a maximum Peak at about 230 nm of Hg2 excimer in high-pressure mercury arc lamp. Comparing the computer- simulated emission spectra with the experimental results, we identify that this 230 nm continuum band is ascribed to the transition of GO state to XO state of Hg2 excimer, and give the fitting value of equilibrium internuclear separations difference Re"-Re'=0.085±0.002 nm.