Based on the previous paper[1], in this work we consider the Maxwell's distribution of atomic velocities, study the near degenerate four-wave mixing effect in transverse Zeeman He-Ne laser by using the vector field model and Lamb's semiclassical theory. We give out the formulas of high-order nonlinear effect, explaine theoretically the physical reason of the beat frequency distortion, and have done the numerical calculation by using computer. The results show that the predictions of theory in this paper are in keeping with experimental results.