The MEMS technology has been developed for many years. Micro-assembly becomes more and more important in this years. Microfasteners play a critical role in micro-assembly due to their simple configuration and easy to be fabricated. The objective of this study is to utilize the phenomenon observed, that fits the definition of the degree of freedom of general mechanisms, and to synthesize new microfasteners employing the concept of mechanism design. Firstly, microfasteners are analyzed based on the need. After synthesizing new microfasteners in micro-scale, they are transformed into compliant mechanisms in micro-scale. By establishing geometry, FEM is applied to simulate the situation of insertion and retention, and to check if bucking will happen. Finally, the retention force is improved by changing the width of links. The insertion force, retention force, and stress are considered for selecting feasible configurations. An example of microgear set mechanism is introduced to demonstrate the assembly of the microgear set after microfabrication process with large backlash.