Abstract: The Dali-Ruili railway is an important part of the south line of the Fanya railway. In order to solve the complex geological problems in railway building, China Geological Survey carried out 1∶50000 regional geological mapping and environment hazard investigation from January 2008 to December 2010. Six working items were set up, which included twenty-two 1∶50000 mapping items and one comprehensive research item. Important progresses were made in such basic geological aspects as structure, petrology, strata and paleontology through systematic regional geological survey. A number of high-precision age data were obtained. The Baoshan block is considered to be a part of the Gondwana continent. Luxi tectonic melange belt was discovered, which is thought to be a part of the Nujiang tectonic melange belt.