In the satellite-to-earth coherent optical communication system, in order to compensate for the wavefront distortion of signal light caused by the random disturbance of atmospheric turbulence, a wavefront coherent compensation technology based on a dual detector array and a stochastic parallel gradient descent algorithm is proposed. Taking the regional light intensity ratio as the beam evaluation standard, an optical communication simulation system integrating signal light wavefront compensation and demodulation is built, and the 65-order Zernike polynomial is used to simulate atmospheric turbulence wavefront distortion. The simulation system adopts quadrature phase shift keying modulation, and the data transmission rate is 10 Gbps. The results show that when the bit error rate is 10-9, the number of photons per bit required by the communication system is reduced to 65.6%, and when the number of photons per bit is 14, the bit error rate is reduced to 2.6%. The wavefront compensation technology based on the dual detector array can compensate the signal light wavefront distortion, reduce the optical communication system error, and provide a guarantee for the signal transmission of the satellite-to-ground optical communication link.