By using Lamb's theory, the concrete calculations for the amplitude and frequency-deter mining equations of laser field with arbitrary J values (total angular momentum of energy level) in the transverse magnetic field are made, the analytical expressions of the first- and third-order coefficients with arbitrary J values and J=1→2 are obtained. As a concrete applicable example, the beat frequency tuning curve of 6328? He-Ne20 transverse Zeeman laser is successfully explained.