Many high-power lasers typically suffer from reduced beam quality due to thermally induced aberrations. Adaptive optics is an effective way to compensate the dynamic aberration. As a key component of adaptive optics system, a novel deformable mirror with 30 mm×30 mm effective reflecting surface and 49 electrostatic actuators has been fabricated successfully for wavefront correction of high average power lasers. The characteristics of this deformable mirror is analyzed and simulated in detail and the simulation result agrees well with the measured result. To meet the requirement of closed loop control, the optical influence function matrix is measured thoroughly. Based on the matrix, the laser wavefront aberration is corrected. From the result, it is explicit that the thermally induced aberration of high-power lasers is compensated by the deformable micro-mirror.