The　piezoelectric　materials　are　used　to　investigate　the　active　vibration　control　of　ordered/disordered　periodic　two-span　beams.　The　equation　of　motion　of　each　sub-beam　with　piezoelectric　patches　is　established　based　on　Hamilton＇s　principle　with　an　assumed　mode　method.　The　velocity　feedback　control　algorithm　is　used　to　design　the　controller.　The　free　and　forced　vibration　behaviors　of　the　two-span　beams　with　the　piezoelectric　actuators　and　sensors　are　analyzed.　The　vibration　properties　of　the　disordered　two-span　beams　caused　by　misplacing　the　middle　support　are　also　researched.　In　addition,　the　effects　of　the　length　disorder　degree　on　the　vibration　performances　of　the　disordered　beams　are　investigated.　From　the　numerical　results,　it　can　be　concluded　that　the　disorder　in　the　length　of　the　periodic　two-span　beams　will　cause　vibration　localizations　of　the　free　and　forced　vibrations　of　the　structure,　and　the　vibration　localization　phenomenon　will　be　more　and　more　obvious　when　the　length　difference　between　the　two　sub-beams　increases.　Moreover,　when　the　velocity　feedback　control　is　used,　both　the　forced　and　the　free　vibrations　will　be　suppressed.　Meanwhile,　the　vibration　behaviors　of　the　two-span　beam　are　tuned.