The fiber laser beam has wave-front aberration, which restricts the performance and efficiency of optic systems. The aberrations′ character of the super-continuum fiber laser beam was analyzed with a building experiment system, and defocus was the main ingredient. According to the character, a prototype of 3-element unimorph DM (unimorph deformable mirror) was manufactured and tested. The simulation accuracy of the influence functions is more than 77% and the frequency response is 12.1 kHz. The results of closed loop correction simulation show that the 3-element unimorph deformable mirror′s correction accuracy for the actual aberration is 0.77. Meanwhile, the finite element analysis is used to optimize the fitting accuracy and displacement. At last a 9-element unimorph DM with the aperture 7.5 mm can reach the accuracy level of about 0.9. The thickness ratio of the mirror and the piezoelectric disk is optimized about 0.3, which further promotes more than 60% of the initial displacement.