Ancient Chinese and modern Chinese are two different forms of language, and there are many differences between them. The biggest difference was the language style. Modern Chinese is modern Chinese. Its language style is relatively concise and clear, expressing its meaning clearly, and its grammar structure is simple. On the other hand, classical Chinese was classical Chinese. Its language style was more quaint, and the vocabulary and grammar structure used were more complicated to express more profound and rich meanings. In terms of expression, modern Chinese emphasized straightforwardness and clarity, while classical Chinese paid more attention to implication and euphemism. For example, when expressing feelings, modern Chinese often directly expressed their feelings, while classical Chinese used rhetoric and metaphor to express their feelings. There were also great differences between classical Chinese and modern Chinese in terms of vocabulary and grammar. There are many vocabulary and grammar structures in classical Chinese that are different from modern Chinese. For example, the terms in classical Chinese are usually expressed in a single word, while modern Chinese usually uses the plurals. In addition, the grammar structure of classical Chinese was more complicated than modern Chinese. For example, the verb and adjective in classical Chinese often could not be directly matched, so they needed to use the word "de" as an auxiliary word. There are great differences between classical Chinese and modern Chinese in terms of language style, expression, vocabulary and grammar structure. These differences reflect the language characteristics and ways of thinking in different historical periods and cultural backgrounds.