The development of the rock mass around the entrance portal of Xiaopingdi tunnel on the ChengduKunming railway is presented in this paper. The maximum diameter and volume of the falling rocks are determined by means of 3D laser scanning technology. The movement characteristics of the falling rocks, including the most likely place the rocks are going to fall, the bounce height of the falling rocks and their energy, are analyzed by means of rock fall simulation. The advantages of using the passive protective net and the steel shed tunnel as the safety measures are analyzed, and comprehensive countermeasures are proposed to cope with rock falls, so as to ensure the operation safety of the railway. The design concept and the rock fall protection structure presented in the paper can provide reference for similar projects in the future.