Wolfgang Amadeus Mozart (1756-1791) was a genius composer who created a wide variety and composition, including about forty symphonies, five violin concertos, twenty-seven piano concertos, concertos (E.g. flute, French horn, bassoon, etc.), 18 masses, requiems, 17 operas and more than 30 serenades, chamber music and piano sonatas, etc.

"Le Nozze di Figaro" was one of the important operas in its creation, it was also a classic work that had been staged so far. "Le Nozze di Figaro" opera was based on the play of French playwright Beaumarchais (1732-1799), by Lorenzo. Up to adapted by Lorenzo Da Ponte (1749-1838). Because of the idea of the Enlightenment at that time, this opera could not be completely presented according to the original work when it was staged, it was through the adaptation of the playwright. Ponte was cut a lot of controversial parts, premiered on May 1, 1786 in the Austrian National Theater in Vienna, and Mozart acted as the conductor himself. During the premiere, the audience was respond enthusiastically, and the solo aria and ensemble were repeatedly encore repeatedly, which caused a sensation at the time.

This paper divided into five chapters, Chapter 1: Introduction. Chapter 2: Mozart and opera works, it understood Mozart's opera works and their characteristics from Mozart's life deeply. Chapter 3: Introduction to the creative background of the opera " Le Nozze di Figaro ", the life of playwrights and adaptors, introduction to the plot, and the role analysis of the countess. Chapter 4: Music analysis and singing interpretation from the two arias of the countess and analyze the structure of the music, the discussion of the lyrics and the interpretation of the song, and deeply explore how to interpret the role of the countess. Chapter 5: Conclusion, the opera " Le Nozze di Figaro " by Mozart was summarized.

I hope that through this research, I will help other researcher through the above chapters able to interpret the corner of the countess more closely.