DMT is the common used line code in the DSL transmission systems, which divided the transmission bandwidth into several hundred subchannels and modulated on each of it with QAM constellation. This article presents the scheme of TTCM that combines turbo codes and bandwidth-efficient TCM to reach more coding gain. Using such coded modulation scheme provides higher transmission rate or longer transmission distance in DMT DSL systems. In order to realize the performance and implementation, the comparison between TTCM and Wei's TCM is performed. This article also presents the large coding gain and accompanied computational complexity of TTCM in DMT DSL systems by Matlab simulation software.