The wavefront phase distortion should be expanded into different orthogonal polynomial combinations for wavefront reconstruction based on modal method. Different orthogonal bases represent different modes of wavefront phase distortion caused by atmospheric turbulence. By calculating the mutual information between the wavefront distortion caused by atmospheric turbulence and each mode, the influence degree of different modes on wavefront distortion is analyzed，and the wave front reconstruction is made in accordance with the established new reconstruction matrix of the mutual information from large to small. The numerical simulation results show that when only one mode is adopted to correct the wavefront, the RMS of the wavefront residual based on mutual information reconstruction decreases from 1.8 rad to 1.15 rad, and the RMS of the traditional mode reconstruction method only decreases to 1.74 rad. When the two modes are adopted to reconstruct the wavefront, the RMS of the residual wavefront of the two methods decreases by 1.2 rad and 0.1 rad respectively. When 65 modes are adopted to reconstruct the wavefront, the traditional mode method has a wavefront residual of 0.2 rad, and when the wavefront residual based on mutual information reconstruction is 0.2 rad, and only 18 modes are needed. Compared with the traditional modal method under conditions of the same precision of wavefront reconstruction, the number of reconstruction modes required for wavefront reconstruction based on mutual information is greatly reduced, reducing the complexity of the reconstruction matrix and improving the speed of wavefront reconstruction.