The guozhaoguan includes Zhengdiau(正調)and Fandiau(反調) melo-metric tunes(唱腔)which are rendered in the Xiluxi(西路戲, the new style theater) of Beiguan theater music in Taiwan. In this study, the primary object of interpretation and analysis will be Fan erhuang daoban(反二黃倒板), Fan erhuang erban(反二黃二板), Fan Erhuang Jinban(反二黃緊板), Fan Erhuang(反二黃) and other Fandian melo-metric tunes, which are not common in Beiguan. At first, go through the story of guozhaoguan to understand the development and compared with the text of Beiguan guozhaoguan. Secondly, analyze the fandiau melo-metric tunes used in Guozhaoguan, clarify and interpret the structure of melo-metric tunes. Finally, discuss the relevance of Xilu Erhuang(西路二黃) and Fulu Pingban(福路平板) to retrospect their source, and compare them to give the evidence that these two melo-metric tunes are from the same acoustic cavity source.