The invention provides a computing method of ground wire loss in an ultra high voltage power transmission line. The computing method of the ground wire loss in the ultra high voltage power transmission line includes: establishing whole simulation models of the ultra high voltage power transmission line through ultra high voltage pole tower simulation models, ultra high voltage line simulation models and ultra high voltage power frequency power source simulation models, which are built, using an electromagnetic transient computing program and an electromagnetic field theory to calculate ground wire loss value in the whole simulation models of the ultra high voltage power transmission line, in various ground wire layout schemes, adjusting parameters so as to obtain the optimal scheme, and adjusting a ground wire according to the optimal scheme. Compared with the prior art, the modules established by using the computing method of the ground wire loss in the ultra high voltage power transmission line conform to practical engineering, are reliable in shape, and accurate and reliable, the ground wire is reliable, scientific and effective to adjust or erect in the practical engineering, waste of a large amount of energy and money is avoided, and the optimum adjustment for the ground wire in the ultra high voltage power transmission line is achieved.