Research conclusions:In order to make railway construction in mountain areas technically feasible, economically reasonable, safe and reliable, the engineering arrangement design thoughts of " giving priority to bridges& tunnels engineering rather than subgrade" must be corrected, the phenomenon of " concentrated and less" arrangement of bridges and tunnels appeared inNanning-Kunming Railway and Neijiang-Kunming Railway should be avoided, and the " pretend subgrade" should be reduced. To any section featured by high filling, deep excavation or major unfavorable geological conditions that may cause engineering diseases, selection should be made following the comparison of schemes ofbridges& tunnels and subgrade comprehensively and taking the factors into account such as rationality in economy, soundness in technology and safety so as to lower the risk of railway construction and operation.