In　low-voltage　power　line　carrier　(LPLC)　communication,　the　traditional　single-carrier　frequency　shift　keying　(FSK)　technology　cannot　adapt　to　the　frequency-selective　fading　due　to　the　resonance　effect　brought　by　the　loads　in　power　line.　To　solve　this　problem,　we　propose　a　multi-carrier　FSK　system　based　on　discrete　short　time　Fourier　transform　(DSTFT).　Meanwhile,　we　present　a　detailed　derivation　on　the　signal-to-noise　(SNR)　estimation　algorithm　based　on　high-order　moments,　which　is　a　key　step　in　the　multi-carrier　system.　Simulation　results　show　that　the　precision　of　the　SNR　estimation　algorithm　is　able　to　meet　the　need　of　a　real　LPLC　communication　system　and　the　multi-carrier　system　can　obtain　better　performance　versus　the　single-carrier　system.　©　2012　Binary　Information　Press.