Abstract: In order to obtain a much finer earthquake catalog in the northern margin of the Ordos Block (2008–2025), we applied tomoDDMC to the seismic data from Inner Mongolia Seismic Network. To obtain reliable results, strict phase selection was conducted prior to location, and results from two different velocity models were tested. The study shows that the spatial distribution characteristics of earthquakes along the northern margin of the Ordos block are not dependent on a single velocity model, but source depths are relatively more influenced by the velocity model. We obtained a total of 2773 recolated events, predominantly small to moderate events with few large-magnitude occurrences. The completeness magnitude M_c was estimated using the maximum curvature method to be approximately 1.3, and the b-value for events with M ≥ M_c was determined using the maximum likelihood method, yielding a value of about 0.54. Significant lateral variations in b-values exist across different regions: relatively low b-values occur near Wuhai-Bayannur in the west and in parts of the central and eastern areas of the study region, while moderate to higher b-values are observed locally around Baotou-Hohhot. The precisely relocted earthquakes exhibit a band-like distribution correlating to the fault’s strike, in which the earthquakes in the western section of the study area are mainly concentrated in the area from Alxa Left Banner to Wuhai, and those in the central section are primarily concentrated in the area from Hohhot to Baotou, while those in the eastern section are mainly concentrated around Horinger. In addition, the dominant focal depths range in 5–15 km, with being deeper in the west but shallower in the east. To quantitatively analyze the characteristics of depth variation, this study divides the region into grids with a 0.5° longitudinal interval and calculates the median focal depths within each longitude band. The results show that the median focal depths range from 3.91 to 16.04 km across different bands, with a variation amplitude of up to 12.13 km. Among them, the highest median depth occurs in the 106.5°–107.0°E band at 16.04 km, while the lowest is found in the 111.0°–111.5°E band at 3.91 km. East of 112°E, focal depths are concentrated between 5 and 10 km and exhibit a gradually shallowing trend.