Yardang fields in arid environments typically exhibit morphological consistency under unidirectional winds. However, the yardangs in Dunhuang Yardang National Geopark in NW China display striking spatial variations-a decades-long paradox unresolved by existing fluvial or aeolian erosion models. To resolve this paradox, we integrated geomorphic mapping, GIS morphometrics (1,000 + yardangs across 5 sub-areas), analysis of micro-erosion features, and regional wind-field validation. Our results demonstrate the aeolian origin of southern yardangs through diagnostic east-west linear textures and echo dunes, refuting dominant fluvial hypotheses. Critically, R-value (length-to-width ratio) gradients decrease southward (from 4.7 to 1.6) and also westward (from 3.1 to 1.6), reaching minima in the central transition zone under synergistic intensification by northerly and easterly winds. Uniform lithology, negligible topography, as confirmed by DEM data, and precipitation patterns exclude non-aeolian controls. Hence, we propose a bidirectional aeolian erosion gradient model: primary winds shape yardang elongation while secondary crosswinds drive fragmentation along spatial vectors. This mechanism, validated against analogues in the Qaidam Basin, advances our understanding of yardang evolution in multidirectional wind regimes. By establishing bidirectional wind erosion as the key driver, our study explains the exceptional morphological diversity of the Dunhuang Geopark, providing the scientific foundation for its unique geotourism appeal.