The　Modular　Multilevel　Matrix　Converter　(M3C)　is　a　high-power　high-voltage　direct　AC/AC　power　converter　topology　which　is　suitable　for　low　frequency　power　transmission　and　distribution　systems,　such　as　offshore　wind　power　integration,　long-distance　FFTS　and　subsea　electric　system.　But　it　has　obvious　non-linear　characteristics,　complex　system　structure,　high　model　order　and　complex　control　task.　Based　on　the　analysis　of　vector　control,　this　paper　proposes　a　high-order　sliding　mode　control　(SMC)　strategy　combining　linear　sliding　mode　with　non-singular　terminal　sliding　mode　to　control　a　high-order　nonlinear　system.　According　to　the　simulation　results　of　the　output　waveform　quality　and　power　characteristics,　the　M3C　has　a　better　performance　under　SMC　than　PI　control.　The　control　strategy　proposed　in　this　paper　can　quickly　and　simply　control　high-order　nonlinear　strongly　coupled　systems,　which　provides　ideas　for　the　stability　control　of　power　systems.　©　2019　IEEE.