Love is an eternal theme in literary works. Throughout the ages, I don't know how many people have fallen for it and sang love songs with passionate feelings. Although we all sincerely hope that all lovers are well, there are still many sad love stories in the history of literature. Romeo and Juliet is one of Shakespeare's famous love tragedies. Romeo and Juliet are lovers in love. They are loyal to their love and vows. In order to get happiness, they ignored any cold reality and finally both committed suicide. It was through the love tragedy of Romeo and Juliet that Shakespeare linked the theme of love with the social contradictions in the Renaissance, criticized the feudal moral concept and showed the humanistic thought of pursuing personal freedom and happiness. Therefore, the socialist religious reform and humanism in this period are a key point of the tragedy, and the characters in the works are also an important factor of the tragedy. Romeo and Juliet, characters, causes of tragedy, religion and humanity abstract love are eternal themes in literature. I still don't know how many people pour out their souls. They sang many passionate love hymns. Although we hope the lovers have a happy wedding, there are still some tragic love stories in literary works. Romeo and Juliet is one of the famous love tragedies in Shakespeare's works. Romeo and Juliet admire each other. They are loyal to their vows and want to be happy, even though the reality is so cold. Finally, they committed suicide. Shakespeare connected the theme of love with conflict in the Renaissance through the tragedy Romeo and Juliet. In this paper, he criticized feudal ethics and expressed his ideal of pursuing personal freedom and happiness. Therefore, the religious reform and humanitarianism are the main causes of the tragedy in this period. The personality of the characters is also the cause of the tragedy of this work. Keywords Romeo and Juliet; Character; The cause of the tragedy; Religion; humanitarianism