A system for transporting signals through PON, including a device for transporting optical network signals and a device for transporting optical line signals, wherein: the device for transporting optical network signals is adapted to map upstream optical signals with a PON frame format to upstream optical channel data unit signals, to convert into upstream signals with an optical channel transport unit format, and to transport to the device for transporting optical line signals through OTN; and to perform corresponding downstream processing; the device for transporting optical line signals is adapted to convert the upstream signals into upstream optical channel data unit signals, to de-map to upstream optical signals with a PON frame format, and to transport to an optical line terminal; and to perform corresponding downstream processing. The invention further discloses relevant devices and methods.