Employing P.R. Banister’s engineering expression for horizontal electric dipole quasi-static electromagnetic field, makes an estimation hereof the peak current moment IL on the basis of the ultra-low frequency observasions for the electromagnetic waves before two esrthquakes: Liyang Ms=6.0 on July 9, 1979 and South Yellow Sea Ms=6.2 on May 21, 1984. The result is: the magnitude of IL=10⁷-10⁸ A.M for Liyang earthquake and the magnitude of IL=10^Ω A.M for South Yellow Sea earth-squake. This is just the same as what we estimated on the principle of crust wavequide.