The invention relates to the field of embedded device firmware burning, in particular to a firmware system data transmission method and a burning device thereof. The transmission method comprises the following steps: S1, starting the PC end, electrifying and starting up the embedded mainboard, and connecting the embedded mainboard with the PC end; s2, starting a PC control module, and calling a native tool to burn ExtBoot to the embedded mainboard; s3, restarting the embedded mainboard and running an ExtBoot system, and reporting a Ready indication signal is reported; s4, after the PC control module receives the Ready indication signal, determining that handshake succeeds, and starting control instruction sending and data transmission; s5, processing, by the embedded mainboard, the instruction and the data and replying the response information; s6, enabling the PC control module to continuously send the control instruction and transmit data until the processing is finished; s7, calling a native tool to burn the firmware kernel to the embedded mainboard, and completing firmware burning of the embedded mainboard. An operator only needs to load the required firmware system data in the transmission unit of the PC control module, and then the firmware system data can be transmitted to the embedded mainboard for burning, so that the method is simple and quick.