Abstract: Taking Miaoziping tunnel of E-Han expressway as the research object, firstly, through the geological survey, tracer test and statistics of the number of karst caves exposed on the site, the characteristics of karst development in the tunnel site are clarified and its control factors are analyzed, and then the engineering influence of karst development is explored based on sorting and analyzing the on-site monitoring data. The results show that: under the coupling action of multiple solution control factors, the karst in the tunnel site shows remarkable characteristics of heterogeneity, concentration, directivity and connectivity. Among them, rock strata lithology, topography, hydrogeology and geological structure mainly make karst development uneven and concentrated; hydrogeology and topography mainly control the direction of karst development and whether karst is connected; climate further promotes karst development. The engineering impact of karst development in the tunnel site area is mainly manifested as the impact of tunnel stability and tunnel water inflow. The scale and size of karst have a certain impact on the stability of the tunnel, but the scope of impact is relatively limited. However, the water inflow makes the tunnel accumulate water for a long time, which even makes the personnel and machinery flooded or destroyed in the rainy season, which has a serious impact on the safety, progress and economy of the tunnel. The conclusion can provide reference for the design, construction, karst disaster prevention and control of tunnel along the E-Han Expressway and other similar projects.