A two-stage lever-type micro-force generator was designed to address the challenges in the calibration system of force sensor to provide accurate micro loads. Initially, the working principle of the micro-force generator was introduced based on the performance comparison among general flexure hinges. Next, the force and energy transmissions were analyzed and a theoretical calculation method to evaluate the minification ratio K was deduced by taking into consideration the deformation of the lever and the offset of the flexure hinge's rotation. To accomplish the aim of achieving a certain minification ratio, the optimization design of the micro-force generator was proposed. Moreover, the response characteristics under different input forces were obtained by performing finite element simulation. Subsequently, a test platform was fabricated to measure the power performance of the micro-force generator. The results show that the largest error between the finite element analysis (FEA) and the theoretical analysis result is 5.501%, whereas that between the experimental result and the theoretical analysis result is 7.391%, the linearity is 2.89%, and loading range of up to 500 μN is reached. The results also indicate that the minification ratio K meets the design requirements and verify the validity of applying the optimization method to design two-stage lever-type micro-force generator and improve the accuracy of micro-Newton loads.