Abstract: With complex geological structures and extensive exposure of carbonate rocks in the middle section of Huaying Mountain, the underground projects have suffered from water inrush disasters of varying degrees and have impacts on the groundwater environment. Current karst studies in the region are insufficient to meet the needs of engineering projects, highlighting the need for a more systematic and comprehensive analysis of the causes of karst water inrush and its effects on the groundwater environment. This study, based on field investigation and extensive data collection of underground engineering water inrush events, utilized groundwater system theory to analyze the groundwater runoff characteristics in the Huayingshan anticline. The study also assessed the influence of the existing Huayingshan Tunnel on highway G42 and the Lvshuidong coal mine engineering activities on the groundwater environment, and explored the potential impact of the new Huayingshan Tunnel of Guang’an−Linshui highway on the karst groundwater environment. The results show that human activities, particularly underground engineering, have altered the hydrology of the central Huaying Mountain area, transforming multiple spring points into reduced or disconnected subsurface river flows, especially in the Tianchi synclinal karst valley and Green Water Cave. The influence area of groundwater is 29.6 km², with the annual displacement of drainage hole of Huayingshan Tunnel on highway G42 of 94.60×10⁴−730.00×10⁴ m³/year; the normal inflow of the new tunnel of Guang’an−Linshui highway is approximately 12.05×10⁴ m³/d, with the influence range of karst groundwater of 1.0−2.1 km. The impact on karst groundwater to the north of the new tunnel is significant, while the influence on the drinking water source and the lake water of Tianchi Lake to the south of the new tunnel is relatively weak. This study can provide basic information and theoretical support for route selection in the Huaying Mountain and parallel ridge-valley area of eastern Sichuan, as well as for water inrush prediction of karst tunnel and ecological environment protection.