Abstract: the paper analyses the existing in the railway roadbed disease are classified, analyzes all kinds of railway roadbed disease occurs, this paper introduces the mechanism of roadbed disease detection method, and points out that the various types of clear roadbed disease and formation mechanism, and the accurate detection is railway roadbed disease prevention and effective governance foundation. Article embankment is band structure engineering, the geological conditions along through the difference is bigger, packing is also not even, and many areas in expansive soil, the red clay, soft rock weathering residual soil underlying engineering properties of soil, and the bad by geography and climate change affects, and because of all the technical level, economic conditions and the construction of the reasons of the mechanical equipment, China's railway roadbed design usually adopts low technical standard, the construction quality often lax, leading to various requirements of railway and become a bed disease wide distribution, management difficult, multiple strong disease, and in recent years with the speed of the train and heavy of subgrade stress level, opens. Distribution condition and functions of the significant changes. Because both railway roadbed design capacity, train speed in smaller after the dynamic stress caused by load under various diseases, leading to produce, or make already existent diseases more serious and the serious influence the safety operation of the train. So understand the type of disease and its occurrence mechanism, and carries on the practical detection, the protection and management of subgrade is very important. Keywords: railway roadbed, disease, mechanism, detection