For example: Maybe the item of travel city include more than one city, But what's the correct writing of Travel City. Should I use Travel City/Cities?
Travel Date: 0503, 2014; 0504, 2014
Travel City: Washington; NY,L.A. etc.
"Travel city" is not idiomatic English. If it is necessary to indicate that more than one destination should be specified, try "destination city/cities" instead, or simply "destination(s)".
If you specify 'destination' (with no suggestion of plural destinations), I think most people would assume you meant 'ultimate destination' -- in other words, the itinerary's last city to be visited.