The　ranking　problem　of　trapezoidal　intuitionistic　fuzzy　numbers　(　TrIFNs)　is　important　and　difficult.　We　define　the　concepts　of　value-index　and　ambiguity-index　based　on　the　value　and　ambiguity　of　the　membership　and　non-membership　functions.　Hereby　a　new　ranking　method　based　on　the　difference-index　is　developed,　and　the　method　possesses　good　properties.　A　numerical　example　is　used　to　illustrate　the　proposed　ranking　method.