The ideas of the Enlightenment, which seeped into not only opera but the whole field of music, and even religion, philosophy, science, and society, had a profound impact on people's ideology. Mozart, as one of the most important composers of the Classical period, had operatic works that transcended the values of his time. Thus it is justifiable that his art creation would be a perfect example for modern scholars to re-exam the notion of enlightenment. This article selects the opera Seria Idomeneo, composed by the composer Mozart in 1781, to study the ideology that it contains and expresses. This opera was born at an important historical point in the transition from the Baroque to the Classical period in the history of Western music and during the famous European Enlightenment of the time. As the first operatic work by Mozart, one of the most important composers of Classicalism, its representational significance is extremely important. With a pictorial map that Burkholder preselected, there will be more and more further interpretative studies on the phrase, the thought of the liberation of individuality, revealed in this opera is reflected in the music, which can be likened to the free expression of emotions. This article provides a brief overview of the enlightened connotations of Mozart's opera Idomeneo, in the hope of establishing a firm foundation for future scholarship on the subject, to better explain the spirit of Mozart's opera as well as his spirit of music.