The mechanical structures of micro-electro-mechanical systems (MEMS) are composed of different types of microstructures, and their mechanical properties are very important for the realisation and reliability of the system performance. One of the key problems in measuring the mechanical properties is the design and implementation of micro-nano displacement driving mechanisms. This paper describes a mechanism that adopts a two-level loading strategy, fast approach, and precise bending displacement loading structures, and has a theoretical analysis and optimal design based on optimal targets of resistance and displacement. The results show that the relative error is 6.98 % for the fast-approaching structure experiment and its optimal simulation and 4.26 % for the precise bending displacement loading structure (PBLS) experiment and its optimal simulation. The optimised micro-nano displacement loading mechanism can achieve optimal output performance under existing constraints.