In some industrial fields such as optical part mold making or fabrication of the nano structure by ultra-precision machinery, an ultra-precision positioning system is widely used. In this paper, an experimental ultra-precision positioning system is designed and fabricated, consisted of an ultra-precision stage supported by flexure hinges, a piezoelectric actuator and an ultra-precision linear encoder. In order to obtain the system transfer function of the ultra-precision positioning system, the frequency response for the sinusoidal input was analyzed. From the bode diagram, the system was modeled in 4th order system. Also, in order to have robustness for the system uncertainty; modeling error and external disturbances, some weighting functions were selected and Hinfin controller was designed. A series of experiments was conducted using the designed Hinfin controller and it was found that this ultra-precision positioning system could be controlled in 5 nm resolution.