Lu Xun's first vernacular essay was 'A Madman's Diary'. This essay was written by Lu Xun in 1918. It was the pioneer work of modern Chinese literature and one of the important milestone in the history of modern Chinese literature. A Madman's Diary was a first-person account of a mentally ill person's resistance and mockery of feudal ethics. The article uses a large number of vernacular and figurative language, concise and lively, full of expressiveness, creating a precedent for modern Chinese vernacular literature. A Madman's Diary caused a great sensation at that time and was regarded as a classic work of modern Chinese literature. It not only had a profound influence on the development of modern Chinese literature, but also laid the foundation for the New Culture Movement in China.