Abstract: With the development of oil and gas fields in deep water, multi-phase pipeline flow assurance technology isfaced with great challenges. The unstable conditions of gas-condensate pipeline can lead to drastic changes of the pipelineoperation parameters and consequently brings serious threat to the safe operation of pipeline. In this paper, LedaFlow, anew type of multiphase transient simulation software, was used to perform steady and transient simulations on a certaingas-condensate pipeline in the working conditions of hydraulic field and thermal field. And the change of temperature, pressure, liquid holdup and total liquid loading along the pipeline under different working conditions were obtained. Itis shown that the calculation results of LedaFlow are correct theoretically and their change trends are in line with thetheoretical expectations. In conclusion, based on above mentioned software calculation, suggestions can be proposed forthe safe operation of pipeline and the design of downstream equipment, so as to provide the references for engineeringpractice.