The geological conditions of the karst terrace of synclinore are complicated. Geological disasters such as water inrush and mud outburst often occur when the tunnel crosses it. The Anping Tunnel was taken as an example. In the early stage of the design of the tunnel route, from the geological perspective, five main geological problems and possible geological disaster risks within the scope of the tunnel route were analyzed and evaluated one by one. And the concept of geological route selection of avoidance without disturbance was used. The route avoidance scheme was selected according to the evaluation results and the horizontal and vertical design indicators were determined. The research results have certain reference significance for geological route selection and route design of tunnels on the karst terrace under similar complicated geological conditions.