A digital Vestigial Sideband (VSB) transmission system and enhanced data multiplexing method are disclosed. When 1/2 enhanced data coded at a rate of 1/2 and 1/4 enhanced data at a rate of 1/4 are transmitted, timing jitter in Moving Picture Experts Group (MPEG) of Vestigial Sideband (VSB) receiver can be reduced and the size of input buffer in Moving Picture Experts Group (MPEG) decoder of the Vestigial Sideband (VSB) receiver can be reduced by multiplexing the 1/2 enhanced data packet and the 1/4 data packet at predetermined intervals. Multiplexing the 1/2 enhanced data packet and the 1/4 data packet by grouping increases the reception performance of the 1/4 enhanced data. Multiplexing the 1/2 enhanced data packet and the 1/4 data packet alternatively reduces the Moving Picture Experts Group (MPEG) timing jitter in the Vestigial Sideband (VSB) receiver and increases the reception performance of the 1/4 enhanced data.