In　order　to　study　the　effect　of　Cr　content　on　the　corrosion　and　stress　corrosion　cracking　behaviors　of　alloys　after　high-temperature　molten　salt　corrosion,　three　typical　pressure　vessel　materials　Q345,　15CrMo,　P91　with　different　Cr　contents　were　tested　in　this　paper.　The　corrosion　behavior　and　the　mechanical　properties　after　high-　temperature　molten　salt　corrosion　were　obtained　by　uniaxial　tensile　tests　and　constant　displacement　stress　corrosion　tests.　The　results　show　that　the　corrosion　resistance　of　the　materials　increases　with　the　increase　of　Cr　content.　With　the　increase　of　temperature,　the　corrosion　products　of　low　Cr　content　alloys　were　sparse　granular,　and　the　corrosion　product　layer　of　high　Cr　content　alloy　was　thin　and　uniform.　The　results　of　uniaxial　tensile　tests　indicate　that　with　the　decrease　of　Cr　content,　the　mechanical　properties　of　the　corroded　materials　showed　unstable　performance,　Cr　content　affects　the　ductility　greatly.　After　565　degrees　C　molten　salt　corrosion,　the　ductility　of　Q345　is　nearly　lost.　The　strength　and　ductility　properties　of　15CrMo　are　relatively　stable　up　to　450　degrees　C,　however,　when　the　corrosion　temperature　is　above　500　degrees　C,　the　mechanical　properties　begin　to　fluctuate.　P91　exhibits　good　performance　in　high　temperature　molten　salt　corrosion　environments.　The　crack　initial　and　growth　behaviors　of　the　crack　tip　change　significantly　under　the　coupling　interaction　of　stress　and　high　temperature　molten　salt.　The　increase　of　Cr　content　aggravates　the　loss　of　fracture　toughness.　The　fracture　toughness　J　Q　of　15CrMo　and　P91　are　99.86　kN/m　and　45.66　kN/m,　respectively.