Atmospheric turbulence is one of the important factors affecting the performance of atmospheric laser communication. Traditional measurement methods have the problems of limited measurement range and influence of environment. Based on the optical phase-locked loop (OPLL) technology in homodyne coherent optical communication system, the atmospheric turbulence intensity is demodulated through the additional phase fluctuation information introduced by the atmospheric turbulence between channels. It can realize the real-time measurement of the atmospheric turbulence intensity in the communication channel with high precision, wide range and high response. Firstly, a theoretical model of the measurement system is established, simulating random phase noise model of atmospheric turbulence under different intensities. Secondly, the homodyne coherent optical communication system is built through software. Finally, the turbulence random phase information is introduced into the simulation system. The simulation results verify the feasibility of the theory and shows that the measurement range of the atmospheric turbulence measurement system is 10^-18 m^-2/3 ~ 10^-12 m^-2/3, and the measurement accuracy is better than 14.8%. The results show that this method has advantages of higher measuring accuracy, wider measuring range and more flexible measurement distance than the traditional measurement methods of atmospheric turbulence, and the results are of great significance for studying the intensity of atmospheric turbulence between channels in atmospheric optical communication system.