Abstract ： Research purposes ： In the investigation of the unfavorable geological body survey of railway engineering, the unfavorable geological body survey， such as faults， ground fissures and gob area， are the key control factors of the control railway alignment. The resolution of conventional geophysical prospecting technology sometimes cannot meet the requirements of the survey， but the shallow seismic reflection method has its unique advantages. In this paper， the author studied how to use the shallow seismic reflection method in the unfavorable geological body survey， obtained perfect application effect, and achieved the purpose of finding out development of the unfavorable geological body，and providing the reliable geological basis for the railway line selection engineering. Research conclusions:(1) Proper sedimentary environment and seismic source excitation condition are the precondition of use of the shallow seismic reflection method. The difference of wave impedance between the surrounding medium and the background rock stratum， because of the existence and activity of the unfavorable geological body， is the basic reason of the shallow sismic reflection method working. (2 ) By using the shallow sismic reflection method which has high resolution，we determined the range of gob area， the position and occurrence of faults， and the development of ground fissures，successfully revealed the geological hazard，and provided the detailed and reliable geological basis for the railway line selection. ( 3 ) The research results and experiences of this paper have extensive promotion significance in the similar railway engineering survey.