<p>In northwestern China, a portion of land around abandoned loess cave dwellings has been reused for cultivation. However, these cave dwellings under farmland are generally more prone to damage triggered by long-term irrigation. Regrettably, how irrigation leads to loess cave dwelling damage is confusing. In this study, a loess gully in Qianxian County, where 61 cave dwellings were once located, was selected as the study area. The patterns of damage on these cave dwellings were investigated and categorized as wall/roof flaking, water penetration, localized roof collapse and complete failure. In addition, the correlations between landuse types over these cave dwellings and the corresponding patterns of damage were analyzed. Furthermore, a miniature cave dwelling model was constructed to simulate the irrigation process, and the average infiltration rate of irrigation water, vertical displacement and vertical stress at the cave roof were monitored. Moreover, we attempt to reveal the mechanism of complete failure via reduced triaxial compression (RTC) tests. The results confirmed that cave dwellings under farmland are more susceptible to water penetration, localized roof collapse and complete failure. It was inferred that water infiltration from irrigation can promote fissure development within the overlying loess, further resulting in fitful water penetration and localized roof collapse. For cave dwellings with limited overlying loess thicknesses, unloading effects triggered by localized roof collapse cannot initiate the sudden occurrence of complete failure. Overall, the evolution of irrigation-induced loess cave dwelling damage is a stepwise process essentially driven by internal erosion.</p>