Triangular　carrier　pulse　width　modulation　(TCPWM)　method　and　the　space　vector　pulse　width　modulation　(SVPWM)　method　are　the　two　main　control　methods　used　in　cascaded　H　bridge　multilevel　converter.　There　is　a　certain　relationship　between　this　two　modulation　strategies,　but　this　relationship　has　not　been　well　studied　so　far.　Thus,　this　paper　studies　the　multi-level　SVPWM　modulation　sequence　and　TCPWM　unity.　By　superimposing　zero-sequence　onto　TCPWM　modulation　wave,　the　same　effect　with　the　SVPWM　modulation　is　achieved.　At　last,　this　paper　deduces　the　unity　of　the　SVPWM　and　TCPWM　in　n　level　with　arbitrary　number　of　segment　sequences.　Simulation　and　experimental　results　verify　the　correctness　of　the　unified　theory.　©　2016,　The　editorial　office　of　Transaction　of　China　Electrotechnical　Society.　All　right　reserved.