Piezoelectric stacks and flexure mechanisms constitute the fundamental forms of micro-displacement positioning. Its comprehensive structure design includes the contradictions between stroke and output force caused by the application requirements. To satisfy the requirement of six degrees of freedom（6-DOF) micro-displacement for ultra-precision machining tools, we put forward a 6-DOF micro-displacement positioning stage, which is driven by piezoelectric stacks and uses flexure mechanism and wedge mechanism for transmission. In order to obtain high micro-displacement precision and high output force of piezoelectric stacks, a certain level preload is needed. On the basis of the relational expression between driven force and displacement in each degree of freedom and stiffness expression obtained by static analysis, the structure of the stage is optimized. Experiment results show that the maximum displacement in x, y, z direction is 7.48μm,8.33μm, and 4.14μm with the resolution of 0.01 μm; the maximum rotation angle in θx, θy, θz direction is 0.13° with the resolution of 0.01°. Therefore, this positioning stage meets the requirements for an ultra-precision machining tool, which means piezoelectric stacks and flexure mechanisms can meet the requirements of both stroke and output force through rational design. The relationship curve of driven voltage and output displacement in each direction obtained by experiments provides the basis for movement and positioning control and also offers the theoretical and experimental basis for the application of flexure hinge mechanism and wedge mechanism in other structures.