Abstract: The communication systems for pipelines completed or under planning, mainly used for telephone service, have a transmission capacity of 34 Mbit/s, which is too low for computer network communication, TV meeting, mulimedium information transmission. In China, SDH system is adopted by Post and Telecommunication Ministry of China and Federal Telecommunication Corperation of China, so as to replace PDH system and expand capacity for better service. The dedicated systems of petroleum industry now have the conditions to adopt SDH system. It is suggested to expand the capacity up to at least 155 Mbit/s for new communication systems.