Based　on　the　internal　friction　of　materials,　the　concept　of　the　mobilized　plane　aims　at　revealing　the　mechanism　of　soil　failure　from　the　perspective　of　geometrical　and　physical　mechanisms.　With　the　characteristic　stress　concept,　the　characteristic　mobilized　plane　under　two-dimensional　stress　conditions　is　put　forward,　and　the　failure　stress　conditions　of　materials　on　the　characteristic　mobilized　plane　and　those　corresponding　to　the　stress　Mohr　circle　are　derived.　In　addition,　based　on　the　existing　understandings　on　the　strength　characteristics　of　the　transverse　isotropic　soils,　and　also　the　relative　positions　among　the　major　principal　stress,　the　normal　of　the　bedding　plane　and　the　normal　of　the　characteristic　mobilized　plane,　the　characteristic　strength　parameter,　as　well　as　the　failure　stress　conditions,　are　proposed　by　projecting　the　microstructure　tensor　into　the　relative　orientation　tensor　between　the　characteristic　mobilized　plane　and　the　bedding　plane.　The　orientation　effect　of　the　bedding　plane　is　also　analyzed　on　the　basis　of　the　proposed　failure　condition.　The　correspondences　of　the　relative　orientation　angle　ζ　between　the　bedding　plane　and　the　characteristic　mobilized　plane　and　the　direction　angle　δ　between　the　bedding　plane　and　the　major　principal　stress,　as　well　as　the　effects　of　ζ　and　δ,　are　also　analyzed.　By　using　the　sample　preparation　mould　developed　for　the　true　triaxial　tests　with　the　freezing　method,　the　samples　with　different　bedding　plane　angles　are　prepared　and　used　to　carry　out　triaxial　compression　tests.　The　understanding　and　proposed　failure　condition　for　the　failure　of　the　transverse　isotropic　soils　are　verified　by　the　predicted　test　results　in　this　paper　and　in　the　literatures.　©　2019,　Editorial　Office　of　Chinese　Journal　of　Geotechnical　Engineering.　All　right　reserved.