The unique phenomenon of Karst in Danxia Landforms may be observed in Langshan, Hunan Province, but there are rare deep exploration about acid erosion to sandstones and conglomerates which are important material foundation in Danxia Landform areas. Base on this point, 41 cores of sandstones and conglomerates were collected from Langshan, 18 cores were selected from them and put into sulfuric acid solutions with three different contents of 2%, 5%, 10%, observed, and recorded continuously for 12 days. Three cores which were not collapsed were undone uniaxial against pressure test at last. The strengths of against pressure of conglomerates declined dramatically after acid erosion, the values to against pressure remained 1/10 only to these rocks in the dry condition. Also the strengths of the 3 cores to uniaxial against pressure after acid erosion were the  lowest in the four sampling sites by analyzing experimental data, so the Danxia rocks in Langshan are easy to collapse and destroy under the same external forces. The reasons of vulnerability to against acid erosion of rocks in Danxia landform are relevant closely to components and structures of those cores by identifications under a polarizing microscope to flakes. Based on macroscopic experimental observations,  general characteristics of against acid erosion vulnerability of sandstones and conglomerates in Danxia Landform areas were micro semi-quantitative analyzed and explained. It is valuable to provide basis for protecting the world natural heritage site and get a sustainable utilization for mankind in the future.