1. A system for measuring a transparent object by fringe projection, measuring a profile or refractive index of an inspected transparent object, the system comprising: a long depth of focus (DOF) image generating device generating a long DOF image, wherein the long DOF image is emitted into the inspected transparent object; an image capture device receiving a distorted image which is generated by the long DOF image emitted into the inspected transparent object and then refracted therefrom; and an image processor electrically connected to the image capture device, wherein the image processor pre-stores the long DOF image, wherein the image processor analyzes the distorted image and compares the distorted image with the long DOF image, so as to identify the profile or refractive index of the inspected transparent object.