A fabrication method for a MEMS structure, the MEMS structure including a fixing portion fixed to the substrate and a floating portion floating above the substrate. A sacrificial layer deposited on the substrate is patterned to have a groove forming a space surrounding the area corresponding to the area in which the fixing portion is to be formed. If the MEMS structure is deposited on the sacrificial layer, a sidewall is formed inside the space and the fixing portion and the floating portion are formed on the sacrificial layer. If the sacrificial layer is removed using an etchant, the sacrificial layer at the bottom of the fixing portion is protected from the etchant by the sidewall and accordingly, the sacrificial layer except the area surrounded by the sidewall is removed. Therefore, only the sacrificial layer under the floating portion is removed. Because the connecting portion is fabricated to have the same thickness as the fixing portion and the floating portion, a strong/durable MEMS structure is provided. Additionally, the boundary between the fixing portion and the floating portion can be precisely determined, and adjustment of the length of the floating portion can be precisely controlled.