A nonlinear model, i.e. the quantized discrete self-trapping equation, is applied to calculate the highly excited CHstretching vibrational energy levels of the CH3I molecule in the liquid phase at the electronic ground state up to n=8.The obtained results agree well with the experimental data and with those obtained from local mode model calculations.We note that the dominant feature of the methyl CH stretching vibrational energy levels of the CH3I molecule is apatte of local mode pairs. When n ＞ 7, all the vibrational energy of the CH3 group can nearly be localized on asingle CH bond.