Abstract: In order to ensure the measuring precision of high accuracy optical, the accuracy of the interferometer reference mirror must be controlled strictly. The influences of different number of adhered points and point distribution, and different support schemes on the shapes of reference mirror were investigated by means of finite element method under gravitational conditions. In order to achieve the peak to valley(PV) value of reference sphere mirror which is better than /40, a kind of support structure of 150 mm reference mirror was designed according to the results of research. The experimental results by means of finite element method indicate that the peak to valley (PV) value and root mean square (RMS) value of the reference surface are only 7.36 nm and 1.52 nm by support scheme with 123 distributed and six-points flexible support, and the thermal deformation is less than gravity deformation. These results demonstrate that all targets validate the rationality of structure and it can well satisfy the requirements.