A method and equipment for dimensional measurement of a micro part based on fiber laser with multi-core fiber Bragg grating probe are provided, wherein a multi-core FBG probe with FBGs (12,29) inscribed in the core or cores out of the center of the multi-core fiber is used to transform the two-dimensional or three-dimensional contact displacement into the spectrum shifts with a high sensitivity. At the meantime, the FBGs in the multi-core FBG probe (12,29) work as the wavelength selection device of the fiber laser, the wavelength of the fiber laser will change thereby. So the contact displacement is finally converted into the wavelength change of the fiber laser. The method and equipment have the advantage of high sensitivity, low probing force, compact structure, high inspecting aspect ratio and immunity to environment interference.