<p>This study proposes a global optimization for the multiple dynamic vibration absorbers (MDVA) system to weaken pernicious torsional oscillations for a damped gas turbine shaft based on dual estimation. The general dynamic model of a damped gas turbine shaft is simplified by converting it to an equivalent undamped gas turbine shaft using the dual estimate. Two globally optimal expressions for the parameters of the MDVA system are suggested based on rigorous mathematical evidence to weaken the torsional oscillations of a damped gas turbine shaft. Numerical simulation results have verified that the globally optimal expressions of the MDVA system suggested in this study generated surprising results for weakening the torsional oscillations of the damped gas turbine shaft. In addition, the results of investigating the influence of the installation location and number of single dynamic vibration absorbers (SDVAs) of the MDVA system have shown that the torsional oscillations weakening effect of the MDVA system enhances corresponding to increases correspondingly with the increase in the number of SDVAs and the farther the installation location of the MDVA system is from the center of the gas turbine shaft. This study provided a powerful tool to optimize the MDVA system parameters to weaken pernicious torsional oscillations of the gas turbine shaft.</p>