The magnetic plasmon (MP) modes in periodic chains of metallic trilayer nanostructures (nanosandwich) have been investigated numerically in optical frequency region. By employing the Fourier Transformation (FT) method, the MP modes excited in these chains can be observed directly.We have also used different exciting sources to excite the MP modes in the chain so that we can get clearer physics picture and richer information of the nanosandwich chain. For their long propagating lengths, the nanosandwich chains can well work as subwavelength waveguides to transport electromagnetic field. And one can easily tune the working frequencies and band width of the MP modes by changing the parameters of these chains.