In this paper we analyze the propagation effect of a rough and ocean-land mixed path on the lightning vertical electric field and azimuthal magnetic field by using Barrick’s formulations and Wait’s formulations. When the lightning-radiated electromagnetic fields propagate from the rough ocean surface to the finitely conducting land section, it is noted that the effect of the rough land section on the fields is much more than that of the rough ocean surface. The propagation effect of a small land section with a few tens of meters length on the electromagnetic spectrum over 2 MHz has to be taken into account, and the lower land conductivity results in a more field attenuation. The lightning fields undergo a sudden decrease near the interface from the ocean to the land section, and the propagation effect of the mixed path on the lightning fields within 10 MHz is primarily caused by the rough land section.