Abstract: The simulation analysis and experimental verification are carried out for the tempering fault that occurred during the development of dual-fuel gas turbine. It is found that insufficient purging gas volume is the key factor to induce the tempering fault. Based on the current situation that the existing air compressor capacity cannot meet the demand of purging, an improved scheme for compressor bleed air and natural gas purging is proposed. Through full-machine verification, it is concluded that the improved measures can effectively avoid the backflow of high-temperature gas in the combustion chamber, and realize the purpose of purging and protecting the non-working fuel pipelines. The research of the paper has reference significance for the development of dual-fuel gas turbine and the design of purging system, and accumulates some experience for the engineering application of similar units.