In　this　paper,　the　study　of　loader　cab　design　based　on　ergonomics.　We　simpled　the　model　of　normal　sitting　position　for　the　loader　cab,　we　establised　mathematic　model　for　many　joint,　and　carried　out　optimization　algorithm　with　Matlab　to　get　the　optimized　schemes.　This　method　will　be　useful　for　design　of　the　internal　space　of　loaders.