Abstract: HYSYS software and PIPESYS software are used to make hydraulic analysis for Pinghu offshore gas pipeline, operating data are used to compare with the softwares calculation results, and the applicable calculation methods of the pipeline pressure drop and the liquid holdup have been obtained. Relation between the transportation pressure, throughput and pipeline liquid holdup as well as liquid holdup formation time are studied in the paper. It is concluded that when the pipeline is operating on the conditions of lower throughput and lower pressure, more liquid holdup will be formed and longer time is needed to form liquid holdup. By means of analyzing the characteristics of condensate gas with HYSYS software, the phase envelope line and hydrate forming curve have been obtained. The analytical results have shown that the hydrate will not be formed during the operation of this offshore pipeline.