A suspension microstructure and its fabrication method, in which the method comprises the steps of: forming at least one insulation layer with inner micro-electro-mechanical structures on an upper surface of a silicon substrate, the micro-electro-mechanical structure includes at least one microstructure and a plurality of metal circuits that are independent from each other, the micro-electro-mechanical structures have an exposed portion on the surface of the insulation layer, and the exposed portion is provided with through holes or stacked metal-via layers correspondingly to the predetermined etching spaces of the micro-electro-mechanical structures, the above predetermined etching spaces and the stacked metal-via layers only penetrate the insulation layer; forming a photoresist with an opening on the upper surface of the exposed portion, and the opening of the photoresist is located outside all the through holes or the stacked metal-via layers; subsequently, conducting etching to realize the suspension of the microstructures.