The measurement of conformal optics is always difficult to perform in the field of ultra-precise manufacturing and measuring. In this paper, a coordinate measuring method based on stitching profile was proposed for the conformal optics. By proposed method, the profile of the conformal optics was divided into several sections with some overlap points, then the every local profile was measured by adjusting the attitude of the measured workpiece, which was completed by the relative movement between the measuring system and the measured workpiece in rotation and transition. Furthermore, an algorithm based on the least square was used to stitch the local profile and to reconstruct the global profile. After those, a mathematical model of the method was established and an iteration algorithm was put forward. An experimental setup was built and the corresponding measurement and data processing software were written with VC and MATLAB, respectively. Finally, an ellipse with a diameter of 120 mm and a length/diameter of 1.2 was tested. Simulations and experiments indicate that the method is practical and simple, and can reconstruct the global profile accurately.