A deep standby method and device for and embedded system is disclosed, wherein the method mainly includes: a selecting step for selecting an available data swap block from the data swap area of a non-volatile memory as a deep standby block; a writing step for writing the current system data and state of the CPU into the deep standby block, and writing a deep standby flag into the deep standby block; and a shutting down step for making the system off to fall into a deep standby.