Groundwater-Dependent Ecosystems (GDEs) in the arid region of northwest China are crucial for maintaining ecological balance and biodiversity. However, the ongoing decline in groundwater levels caused by excessive groundwater exploitation poses a potential threat to GDEs. This paper reviews the current developments and future challenges associated with defining groundwater level thresholds for maintaining GDEs in arid regions. It focuses on methods for identifying and investigating these thresholds, with particular attention to recent advances in northwest China. Additionally, this paper highlights the limitations and future challenges in determining these thresholds, including the complexities of ecological processes, groundwater systems, data availability, and methodological constraints. To address these issues, a multidisciplinary approach that incorporates new technologies, such as multi-source data fusion, machine learning models, and big data and cloud computing, will be essential. By overcoming these challenges and utilizing effective methods, appropriate groundwater level thresholds can be established to ensure the long-term sustainability of GDEs.