The opera started and developed in 11th to 13th century. The mid-to-late 19th century was the "golden age" of opera which established and dominated by Wagner in Germany and Verdi in Italy. In this golden era, some of the instrument players also try to select some famous arias from the operas to compose a new works in “fantasia” format. So far, there are still many people acquainted with operas because of the fantasias and the fantasias facilitate the popularity of the operas. The well-known Italian clarinet player, Luigi Bassi, (1833–1871) wrote 15 operatic fantasias. The notably works include “I Puritani” of Vincenzo Bellini(1801-1835) and “Rigoletto” on Verdi's. The “Cavalleria Rusticana Fantasia for Clarinet and Piano” was composed by Carlo Della Giacoma (1858-1929) and the basic themes of melody are inspired from the arias of “Cavalleria Rusticana”, the Italian opera created by Pietro Antonio Stefano Mascagni(1863-1945). These arias are “Siciliana”, “E stamattina, all’alba”, “Stornello di Lola”, and “Viva il vino spumeggiante”. In addition, the famous intermezzo and the aria “Mamma! Mamma, quel vino è generoso” were organized as bridge to enrich the musicality. Carlo Della Giacoma applied the embellished melody to compose this variations on a theme, of note, his fantasia works also demonstrate a major technological breakthrough of clarinet. This thesis not only compare the opera and fantasia by analyzing the music style and discussing the interpretation, but also try to offer a good model to the clarinet player who wants to interpret this work.