Highlights What are the main findings? Drought in Inner Mongolia grasslands (1961-2012) shows clear spatiotemporal patterns: drought frequency decreases with severity, is higher in the central-western regions (nine droughts in ten years), intensity increases westward, and duration lengthens with rising severity. Drought is the dominant driver of grassland NPP variation (explaining up to 84% of NPP anomalies), with meadow steppe being the most drought-sensitive and desert steppe the most resilient; drought impacts on NPP, hay yield, sheep units, and economic loss amplify linearly with severity (extreme drought causes 2.8 & times; higher Npp loss, 1.1 & times; higher hay loss, and 4.4 & times; higher economic loss than moderate drought). What are the implications of the main findings? It provides a scientific, quantifiable basis for drought risk early warning and graded prevention in Inner Mongolia and similar arid-semi-arid pastoral areas, supporting targeted governance based on drought severity and grassland type. The validated assessment chain offers a replicable tool for dynamic monitoring and loss evaluation of pastoral drought, helping policymakers optimize grazing management, allocate relief resources, and improve the resilience of grassland-livestock systems under climate change.Highlights What are the main findings? Drought in Inner Mongolia grasslands (1961-2012) shows clear spatiotemporal patterns: drought frequency decreases with severity, is higher in the central-western regions (nine droughts in ten years), intensity increases westward, and duration lengthens with rising severity. Drought is the dominant driver of grassland NPP variation (explaining up to 84% of NPP anomalies), with meadow steppe being the most drought-sensitive and desert steppe the most resilient; drought impacts on NPP, hay yield, sheep units, and economic loss amplify linearly with severity (extreme drought causes 2.8 & times; higher Npp loss, 1.1 & times; higher hay loss, and 4.4 & times; higher economic loss than moderate drought). What are the implications of the main findings? It provides a scientific, quantifiable basis for drought risk early warning and graded prevention in Inner Mongolia and similar arid-semi-arid pastoral areas, supporting targeted governance based on drought severity and grassland type. The validated assessment chain offers a replicable tool for dynamic monitoring and loss evaluation of pastoral drought, helping policymakers optimize grazing management, allocate relief resources, and improve the resilience of grassland-livestock systems under climate change.Abstract Drought, one of the most severe natural disasters globally, has inflicted notable impacts on animal husbandry production, yet the current research on drought impact assessment in pastoral systems is plagued by obvious gaps, such as the lack of comprehensive quantitative evaluations integrating grassland ecosystem and livestock production indicators, unclear quantitative relationships between drought severity gradients and multi-level pastoral impacts, and the absence of validated quantitative assessment frameworks linking drought indices with actual pastoral economic losses. To fill these gaps, this study takes Inner Mongolia grasslands as the research area, analyzes the spatiotemporal characteristics of drought and its impacts on grassland net primary productivity (NPP) over the 50-year period from 1961 to 2012, and quantifies the differential impacts of three representative gradient drought events (1974 moderate, 1986 severe, and 1965 extreme) on grassland NPP, standard hay yield, sheep units and livestock economic losses. The long-term analysis shows that drought frequency in the study area decreases with increasing severity, with the typical steppe having the highest drought frequency and a "nine droughts in ten years" pattern in the central and western regions; drought intensity increases westward, and duration extends with rising severity, and its spatial distribution is highly consistent with the east-west precipitation gradient. Drought is the dominant driver of NPP variation, explaining up to 84% of NPP anomalies, with meadow steppe being the most sensitive to drought and desert steppe showing stronger drought resilience due to adaptive traits such as deeper root systems. The assessment of the three representative drought events reveals that drought impacts exhibit a linear amplification effect with severity, with extreme drought causing an average NPP loss 2.8 times greater, hay yield loss 1.1 times greater, and economic loss 4.4 times greater than those caused by moderate drought, and different grassland types show distinct response characteristics to drought of varying severity. The NPP loss spatial distribution is highly consistent with severe drought areas, and sheep unit loss is directly correlated with drought severity. Most importantly, the study validates a robust quantitative assessment framework (SPI -> NPP -> hay yield -> sheep units -> economic loss) with relative errors of less than 9% compared with historical disaster records, which systematically links drought indices with practical pastoral economic losses. This research clarifies the quantitative relationships between drought and multi-dimensional pastoral impacts, and provides actionable scientific insights for drought risk governance in arid and semi-arid pastoral areas such as Inner Mongolia.