A signal transmission system of a flat panel device includes an encoder, a transmitter, a receiver, and a decoder. The encoder converts a digital signal to a switch control signal. The transmitter includes 4n signal-lines for transmitting a current signal according to the switch control signal. The receiver includes 4n terminations, a plurality of terminal resistors, and a plurality of comparators. The receiver generates a group of voltage levels according to the current signal. Each comparator is coupled between any two terminations so as to generate a group of voltage differences. The decoder converts the group of voltage differences to the digital signal.