Three DOFs elastic support for fast steering mirror driven by piezoelectric is designed in order to effectively absorb the lateral deviation of driving point caused by tilting of mirror, protect the piezoelectric drivers, restrain the DOF in non-working direction and enhance the frequency resonance of system. Firstly the scheme of all-around elastic support which consists of flexure ring and flexure staff was determined according to requirements of fast steering mirror driven by piezoelectric design. Secondly flexure ring and flexure staff was designed separately based on the buckling theory and energy theory. Finally the design was analyzed with FEA software workbench. The FEA analysis shows that the sheer displacement of piezoelectric decreases 86.7% with the application of 8 mm length and 1mm diameter flexure staff. In addition, the application of flexure ring turns the axial translation vibration into the first- rder mode with resonance frequency of 340 Hz，turns the swing vibration into the second and the third order mode with resonance frequency of 420 Hz and the higher-order resonance frequency is more than 1 000 Hz. The three DOFs elastic support can prevent piezoelectric from sheering damage and help to enhance the resonance frequency of fast steering mirror system, which does help to enhancing the close-loop bandwidth of the system.