The application of continuous electromagnetic profiling (CEMP) to Ruoqiang sag of the southern Altun Mountains is described in this paper. Because of the undulating landform, static electromagnetic effect is serious, and underground resistivity varies considerably. Robust processing applications, static correction and CEMP handling with terrain two-dimensional continuum inversion imaging can yield high inversion precision in line with the actual situation. Making full use of the complementary advantages of seismic and non-seismic survey, the author established the structural interpretation model so as to deepen the understanding of the geological structure. It is detected that the left twisting slip of the Altun fault system caused the formation of piedmont 3 groups of NEE-striking faults parallel to the Altun Mountains, and that the strike slip movement caused the piedmont depression to exhibit the concave and convex tectonic pattern of the Altun Mountains in Ruoqiang sag. It is inferred that the long distance overthrust nappe towards Ruoqiang Sag made the Proterozoic Paleozoic strata thrust onto the Mesozoic strata, and therefore Altun forelands possibly have covered Jurassic strata characterized by large thickness, great burial depth and relatively high maturity.