Transient Electromagnetic Method (TEM) exploration was carried out in the Tianyu Cu-Ni deposit of eastern Xinjiang to sum up the geophysical characteristics of magmatic sulfide Cu-Ni deposits related to mafic and ultramafic rock bodies. In this paper, the characteristics of TEM response, time constant and resistivity for orebody, fracture and rock body are summed up from in-loop and borehole TEM data. Experiments show that the decay curves of the orebody decay slowly and the gradient of the late channels is about 1.3~1.5 at double logarithmic coordinate, with its apparent time constant being about 0.5ms. The TEM response of background decays is quicker than that of the orebody with its gradient being about 2.7 and its apparent time constant being about 0.23 ms. The apparent resistivity of the orebody from the inversion data is below 200Ω·m, while that of the background is higher than 500Ω·m. Fractures are distributed in the transition zone of high resistivity and low resistivity. The application effect of the TEM is good in the sulfide Cu-Ni deposit, and can provide some reference for exploration of the same type deposits.