As "ecological guardians" in national park development, relocated ecological migrants have made significant contributions to environmental conservation. Yet as "subjects with restricted development rights," they face multidimensional poverty challenges—including income levels, livelihood capabilities, and quality of life—during their transitional adaptation. Common prosperity is an essential requirement of socialism with Chinese characteristics and a defining feature of Chinese modernization. Against this backdrop of advancing common prosperity, an in-depth investigation into the multidimensional relative poverty of these households holds critical significance. By clarifying how ecological relocation impacts their poverty dynamics, this research provided key insights for synergizing ecological protection with livelihood improvements—ultimately supporting the realization of common prosperity. Through establishing a theoretical analytical framework for assessing the effects of ecological migration on multidimensional relative poverty of farmers, this study employed micro-level survey data from 585 households in the Qinling area of the Giant Panda National Park, utilizing a two-stage least squares model, mediating effect model, and moderating effect model to empirically examine the transmission mechanisms and regulatory effects of ecological migration on multidimensional relative poverty. This study mainly addressed the following questions: First, what impact has ecological migration had on the multidimensional relative poverty of farmers in national parks? Has it alleviated or exacerbated the situation? Second, what is the transmission mechanism through which ecological migration affects the multidimensional relative poverty of farmers? Third, can national park policies strengthen or weaken the impact of ecological migration on the multidimensional relative poverty of farmers? The findings included: (1) Structural disparities existed in multidimensional relative poverty among national park households, with non-economic dimensions—such as heating accessibility, educational burden, and safety perception deficits—exhibiting pronounced deprivation. (2) Ecological migration can significantly alleviated the multidimensional relative poverty of households in national parks. (3) Labor allocation and agricultural capital investment play a partial mediating role in the impact of ecological migration on the multidimensional relative poverty of households. (4) The regulatory policies and compensation policies of national parks exerted a negative moderating effect on the impact of ecological migration on the multidimensional relative poverty of households. Drawing on the aforementioned findings, this study put forward context-specific recommendations from establishing a three-tier publicity network and strengthening non-economic support in resettlement areas, promoting labor skill transformation and market-oriented reform of capital factors, and optimizing the policy portfolio for national parks with flexible transition mechanisms. Through institutional innovation, factor activation and policy coordination, the system achieves organic integration of ecological conservation and livelihood development.