How to support the Mirror, especially the primary mirror is one of the most difficulties to design a large aperture and long focal length collimator. The number and the location of support points for collimator primary mirror are optimized. The diameter of primary mirror is 1 000 mm. The formidable optimization analysis module of ANSYS is used to optimize the primary mirror’s model in condition of 3, 9, 18, 24 and 27 different points support. Also, static analysis of five different numbers of points support in gravity field is simulated. From the displacements of five mirror models, the values of PV and RMS respectively are calculated. To satisfy the requirement of PV and RMS, the best case can be given-18 points support.