Abstract The harmonic drive mechanism has been used wildly in industrial robots. High reduction ratio, few components, and quiet torque transfer are the advantages of this device. In this thesis, the dynamic characteristic of an integrated DC motor and harmonic driver system is investigated. The dynamic equations of the harmonic drive systems are derived by applying Lagrange¡¦s equation. Two different harmonic driver designs, i.e. a cup-type with two teeth difference and a circular type with four teeth difference are used in the analysis. The system responses are simulated by employing the sixth order Runge-Kutta method. Comparison between numerical simulation results and experimental results, it indicates that the proposed model is feasible and accurate for simulating the dynamic response of an electro-mechanical integrated harmonic drive system.