This paper presents the free vibration response of orthotropic stiffened plates structure. The free vibration analyses are performed for the orthotropic plates by using the commercial finite element software ANSYS Parametric Design Language (APDL). Numerical results obtained by the finite element method are compared with published results. For stiffened orthotropic plates, the effects of number, orientation, and types of stiffeners; aspect ratios of plates, and different fiber orientations on the fundamental natural frequency are presented for different boundary conditions. The present research shows that stiffened plates are superior to unstiffened plates and the frequency of the stiffened plate increases as the number of stiffeners increases Thus, the present paper highlights some important characteristics of an orthotropic plate with a stiffener that can be useful in the design of structures made of composite.