High-speed nano-positioners are widely applied in semiconductor manufacturing, adaptive optics, scanning probe microscopy and motion tracking. In fast steering nano-positioners, high displacement resolution is commonly achieved through piezoelectric stack actuators. This paper proposes a novel lever mechanism to amplify the command motion of piezo-stack actuator, while ensuring a high actuation bandwidth. A lumped parameter model has been developed for the initial design of the flexure-lever amplifying mechanism. Through a stepwise intuitive approach to design, a novel structure based on trusses is proposed for the lever to reduce its mass while maintaining a high stiffness, thus resulting in an overall high resonant frequency. Further mechanisms are integrated to apply a compressive preload to the piezo actuator and ensure its point of contact with the lever. Through Finite Element Analysis, the overall structure has been validated for an amplification gain of 3.8, while having a high eigen frequency of more than 1.1 kHz.