<p>The North China Craton exhibits a striking geological contrast between the eastern and western segments. Since the Mesozoic, the eastern region has undergone extensive lithospheric thinning and destruction, whereas the western Ordos Block has been characterized by long-term tectonic stability. The mechanisms underlying this differential evolution, however, remain debated. The northern Ordos Block, with its well-preserved tectonic structures, continuous sedimentary cover, and minimal surface erosion, offers an ideal setting to investigate intracratonic stability. Here, we integrate multi-frequency receiver function analysis with Pn multiple-phase imaging to construct a high-resolution crustal velocity model, spanning from the sedimentary cover to the Moho, along a ∼500 km broadband seismic array across the northern Ordos Block. Results reveal a thick and continuous sedimentary cover within the basin (up to 4.6 km), overlying a ∼39.5 km crystalline crust, giving a total crustal thickness of 42.9±0.8 km. This Moho is flat, and the velocity structure is laterally uniform, showing typical cratonic features. The crystalline crust has an average P-wave velocity of 6.5±0.05 km s⁻¹ and a P- to S-wave velocity ratio of 1.75±0.04, corresponding to a mean SiO₂ content of 53.5±2.1 wt%, indicative of an intermediate to mafic composition. These results support the tectonic model that the Ordos Block originated as an Archean oceanic plateau. The eastern margin shows crustal thickening accompanied by sharp sedimentary thinning. Isostatic analysis reveals that variations in crustal thickness, sedimentary erosion, lithospheric mantle structure, and mantle-derived magmatism jointly regulate surface elevation, reflecting a coupled isostatic response between shallow and deep processes. This study provides new seismological evidence for the internal stability of the Ordos Block and offers insights into the long-term preservation mechanisms of the cratonic lithosphere.</p>