Abstract: The processing and interpretation of the data derived using the transient electromagnetic (TEM) method are still mainly conducted through one-dimensional (1D) inversion presently. Therefore, developing an efficient and stable 1D inversion system with complete functions is greatly significant for further promoting the applications of the ground-based loop-source TEM method in China. This study developed such an inversion system, which involves four methods, namely minimum-structure inversion, Occam's inversion, laterally constrained inversion (LCI), and spatially constrained inversion (SCI). The first two methods are based on the Gauss-Newton method, and the others are based on the damped least-square method. This 1D inversion system was applied to detect the occurrence forms of the basalt rock masses in the Narenbaolige coalfield in Inner Mongolia. Then, the results derived from the minimum-structure inversion and Occam's inversion used in the 1D inversion system were compared with those obtained using the commercial software IX1D. As shown in the 2D pseudosection maps of resistivity obtained by these inversion methods, the basalt rock masses have similar occurrence forms and consistent resistivity range. Compared with drilling data, these 1D inversion results clearly reflected the distribution patterns of basalt rock masses in the Narenbaolige coalfield except for the upwelling channels of magmas. Afterward, the LCI and SCI were also applied to the coalfield. The results indicate a decrease in the resistivity differences of the basalt rock masses between adjacent survey points and an increase in the continuity of the interfaces between the basalts and sedimentary rocks.