Aecording to Parisi's suggestion, we assume that the gluon possesses a non-zero effective mass μ. From this assumption, we derive an effective Hamiltonian up to order β2 for quarkonium. For μ = 0.8 GeVand 0.4 GeV, we find the spectra as well as the relative leptonic widths for charmonium and upsilon, which are in good agreement with experiment.