Abstract: The main engineering geotechnical problems were the existence of rocks and soft soil in the shallow entrance, the two lager faults, karst and karst water, and gas in Tanchang tunnel. The four main issues focused on the entrance of the tunnel, which made the tunnel construction difficult and the risk increased greatly. Analysis of these issues was done in detail, the comprehensive geological prediction technology in construction period and the corresponding contingency plans for construction were proposed. By the geological prediction of construction period and the implementation of the tunnel excavation verification, the tunnel project construction was done safety under the guidance, complex engineering geological problems of the tunnel were solved and the construction quality was protected.