In the azimuth transfer system based on magneto-optical modulation, the magnetic field of a magneto-optic material based built-in solenoid driven by alternating current is very important and directly related to the azimuth transmission accuracy. This paper presents the effect of the solenoid paraxial magnetic field driven by alternating current on the azimuth transmission accuracy. First, an electromagnetic field model of a hollow solenoid is constructed using the Maxwell equation, and the influence of the driving signal frequency on the magnetic field is analyzed. Then, a magnetic field model of the built-in solenoid based on magneto-optic material is established according to the ampere loop law. Finally, the effects of a non-relaxation polarization medium, a relaxation polarization medium, and driving signal frequency on the azimuth transmission accuracy are analyzed. The results demonstrate that the driving signal frequency is an important factor affecting the system azimuth transmission accuracy, and the error of the azimuth transmission is regular. The effects of the non-relaxation and relaxation polarization media on the system azimuth transmission accuracy are similar. We expect that these results will provide a reference for further analysis on azimuth transmission accuracy and system optimization design.