The work aims to investigate the use of a vibration-based damage detection method incorporating a chaotic oscillator for identifying the depth of delamination in a composite laminated panel. A type of non-linear oscillator, called the Duffing oscillator, is used for analyzing vibration signals measured from a composite laminate in order to identify the depth of delamination due to its excellent sensitivity to the dynamic change in vibration signals and its robustness to measurement noise. A composite laminated panel with delamination at varying composite layers is investigated through numerical simulation studies. The measured vibration signal is analyzed by using the Duffing oscillator and the change of its dynamic characteristics with respect to delamination depth is measured by using the Lyapunov Exponent (LE) feature. The relationship between the LE feature and the depth of delamination is investigated. The results demonstrate the effectiveness of the method for identifying the depth of delamination in composite laminates based on vibration measurements.