Based on the investigation on the strategy, effect and experience in the purging of super high pressure steam pipelines, this paper takes the Ethylene Project Phase II in Zhenhai as an example to analyze from the economic point of view the huge differences in commissioning cost due to different treatment methods for the internal cleanliness of super high pressure steam pipelines while meeting the quality and environment protection requirements of the system. The results show that safety and environment protection can be improved and great achievements can be made in energy saving during the commissioning of the new plant by continuously using new technologies and new ideas and optimizing the commissioning plan.