The　confining　pressure　effect　of　the　shear　strength　of　frozen　soil　is　the　basis　and　prerequisite　for　analysing　the　bearing　capacity　of　engineering　construction　in　cold　regions　and　the　engineering　project　constructed　by　the　artificial　freezing　method.　As　the　confining　pressure　increases,　the　existing　test　results　of　shear　strength　of　the　frozen　soils　show　both　a　two-stage　law　that　increases　first　and　then　decreases,　and　a　three-stage　law　that　increases　first,　then　decreases　and　then　increases　again.　In　order　to　characterize　the　special　development　of　the　shear　strength　of　frozen　soils,　properties　of　soils　and　ice　are　analysed.　It　is　believed　that　the　shear　strength　of　frozen　soil　presents　a　multi-stage　development,　not　only　because　it　inherits　the　strength　characteristics　of　the　soil,　but　also　because　the　existence　of　pore　ice　makes　a　special　contribution　to　shear　strength.　On　the　basis　of　the　above　analysis,　the　shear　strength　of　frozen　soil　is　decomposed　into　the　base　strength　reflecting　the　cohesive-friction　properties　and　the　special　contribution　strength　of　pore　ice　to　the　shear　strength　of　frozen　soil.　By　adopting　the　power　function　strength　expression　as　the　base　strength　of　frozen　soil,　and　further　establishing　the　contributed　strength　describing　the　strengthening　and　weakening　rules　of　frozen　soil,　a　three-stage　strength　criterion　incorporating　the　confining　pressure　effect　is　developed　for　frozen　soils.　The　comparison　between　the　test　results　of　frozen　soils　in　different　types　and　the　predictions　shows　that　the　established　strength　criterion　is　capable　of　capturing　the　variation　rule　of　shear　strength　of　frozen　soils.　©　2023　Tsinghua　University.　All　rights　reserved.