In　terms　of　creating　customized　products　rapidly,　modularity　is　deemed　to　be　an　effective　developmental　strategy　for　handling　product　variety　and　intricacy.　In　order　to　develop　reasonable　modular　product　architecture　with　physically　detachable　modules,　a　new　systematic　and　structured　approach　for　product　modularization　based　on　axiomatic　design　and　design　structure　matrix　is　proposed.　The　product　is　decomposed　hierarchically　into　its　functional,　physical,　and　process　domains　using　axiomatic　design　method.　After　transformation　from　design　matrix　to　design　structure　matrix,　the　pertinence　design　structure　matrices　of　design　parameters　describing　function,　structure,　and　manufacturing　process　are　constructed.　Besides,　a　manufacturing　process　similarity　matrix　of　design　parameters　is　established.　Finally,　a　genetic　algorithm　combined　with　the　minimal　description　length　is　employed　to　realize　the　modularization　optimization　after　integration　of　the　above　matrices.　To　illustrate　the　effectiveness　of　the　proposed　methodology,　an　indoor　air　conditioner　unit　is　presented　as　a　demonstrative　example.