The prototype of mold oscillator that uses a non-sinusoidal generator was modified using Inverse dynamics and Multi-body dynamics. We maintained a basic structure of the mold oscillator including the motor, the gear, the leaf-spring and the caster. To reduce the coupling effect, the non-sinusoidal generator was replaced by a hollow cylinder that had non-sinusoidal surface. The system parameters were obtained from previous research [1], and a new design of the connecting rod between the cylinder and the leaf spring was analyzed by sensitivity analysis. A definition of the detailed system component including gear mesh, and non-sinusoidal surface, Lagrange's equation, Fourier series, and Cam profile synthesis was used to define an equation of motion. The response of oscillating system was derived by a direct integration method. The model was simulated according a specific assumption for each component, and a control system corresponding to real operation was applied. Dynamic responses are displacement, velocity and acceleration of each component. All responses from these simulations were analyzed in the time-frequency region by Fast Fourier transform. Using the model, sensitivity analysis about design variables was also executed about operating performance.