A data transmission method and system for enhanced channel coding efficiency of a DisplayPort interface is disclosed. One method comprises transmitting a plurality of coding units for each micro-packet in each of one or more lanes of a DisplayPort Main Link from a DisplayPort transmitter, wherein each of the coding units comprises: a group of m symbol chunks, each symbol chunk including four 8-bit symbols, wherein m is 2 or 4; and an n-bit code data indicator that precedes the group of m-symbol chunks, wherein n is 2 or 4, and wherein the n-bit code data indicator indicates a content type of the m symbol chunks.