Abstract: According to the status of the very soft layer in east inner mongolia such as poor cementation，large deformation of open-off cut，poor molding of roadway and great difficulty in roadway support，the reasonable supporting techniques of open-off cut pilot tunnel in the very soft layer are discussed by the numerical calculation of FLAC3D. Based on these，the paper proposes the combining support scheme of anchor rope and shape steel bracket and the reasonable parameters. And based on theoretical calculation and the numerical calculation of ANSYS，the bearing capacity of shape steel bracket and its reasonability are proved to guarantee the stability and safety of the surrounding rock and supporting structure in the very soft layer. The supporting scheme and parameters are verified to be reasonable by field monitoring，thus providing a reference for supporting techniques of open-off cut pilot tunnel in the very soft layer of the east inner mongolia.

Key words: The very soft layer, FLAC3D, Open-off cut, ANSYS, Supporting techniques