Abstract: Location of line in a mountainous environment in which active structures are well developed is a major engineering-geological problem concerned in railway and highway construction.In light of a study of the location of the Yu-Meng section of the newly built Kun-He Railway in southwestern China,the paper discusses the regional characteristics of internal and external dynamic geological processes and major engineering-geological problems such as the geological environment,neotectonic movement and earthquakes,active faults and seismic risks and mountainous hazards,and demonstrates and compares the optimized schemes of line orientation based on the engineering geological conditions and economic and technical aspects.This study may be used as reference for the railway and highway location in mountainous areas with a similar regional geological environment.