A new kind of adaptive optics (AO) system, in which several deformable mirrors (DMs) with optical conjugation relationship are combined to improve wavefront spatial correction capability, is proposed. The surface displacement of combinational deformable mirror (CDM) is introduced. Based on theoretical analysis, the integrated AO system with CDM that consists of two same deformable mirrors with the square arrays is built. The correction performance for the first 35 order Zernike aberrations is calculated and its closed-loop effect for correcting real aberrations is validated experimentally. The results indicate that CDM in the AO system can correct aberrations effectively as the same as one single DM with more actuators by using the direct-gradient control algorithm steadily in closed-loop, and the correction capability of the CDM is better than that of only one DM. This design can improve wavefront spatial correction capability by increasing the number of actuators and the coupling coefficient. So it can be used for compensating high-order aberrations instead of one single costly DM with more actuators for the same performance.