Abstract: Elaborated in the paper are the application of the X80 linepipes to Line No.2 of the West-East Natural Gas Transmission Project,and the recent progress of the R & D of the linepipes in Steel Grades X90,X100 and X120. It is recognized that great progresses have been achieved in the R & D of hi-strength and extra-hi-strength steel linepipes over the resent years. Nevertheless,to a certain degree,the domestic research on suitability of the X100 steel linepipe is still lapping behind the international level.