Using stimulated emission pumping, the Na2 molecule is excited to Na2 X 1 Σ + g ( ν″ =33, J″ =11) high vibrational state, and the state- state energy transfer processes of the highly excited Na2 and CO2 are studied. Scanning Na2 X 1 Σ +g (33, 11)→ A1 Σ +u (21, 10) transition by narrow linewidth laser and monitoring its transmission light intensity, the original population density of Na2 [ X 1 Σ +g (33, 11)] is measured from absorption coefficient. Using highresolution transient absorption measurement technique, the distribution of CO2 rotational population in the ground (0000) state is determined. Through the analysis of rate equation, under the single- collision condition, the rate constants of CO2 (0000) high rotational state in the collisions with highly vibrationally excited Na2 are obtained. For J=46~64, the rate constants have been measured in 4.5×10-12~6.5×10-13 cm3s-1. Relatively to the J state, the quenching rate constants of Na2 ( ν″ =33) have been determined in 2.3×10-11~9.1×10-11 cm3s-1. The experimental data show that in the collisional energy transfer between highly vibrationally excited Na2 and CO2, the increase of CO2 rotational energy is much more sensitive to collisional depletion of excited state Na2. Multiquantum relaxation of highly vibrationally excited Na2 is observed and the relaxation rate constants have been obtained.