Brief introduction to microsystems 2 Discussions on the developments of microsystem technologies 3 Applications of electrochemistry in microsystem 3.1 Confined Etchant Layer Technique (CELT) for the complex 3D-pattern micromachining 3.2 Focusing Electrophoresis and the application of microsystem in (bio) chemistry (μTAS or Lab on A Chip) 3.3 Smart Electro-Osmosis pump——a reasonable choosing for microfluidic network 4 Concluding remark