In this paper, a new parallel nanopositioner (PNP) employing a spatial compliant parallel manipulator has been proposed due to the excellent accuracy of parallel mechanisms and flexure hinges. The system is established by a proper selection of hardware and analyzed based upon the derived pseudo-rigid-body model. In view of the physical constraints imposed by both the piezoelectric actuators and flexure hinges, the PNP's reachable workspace is determined analytically, where a maximum cylinder defined as usable workspace can be inscribed. Moreover, the optimal design of the PNP with the consideration of the usable workspace size and global dexterity index simultaneously is carried out so as to make a compromise between the two separate performances by utilizing the efficient genetic algorithm. And the optimization results will be valuable in the design of a new nanopositioner. ©2006 IEEE.