Abstract: Through a detailed survey of 50 often used Chinese unit words from Han Yu Da Zi Dian and Han Yu Da Ci Dian，this essay analyzes the formation of the original meaning and semantic changes of these unit words.The study reveals that unit words in Chinese have various origins according to part of speech，word meaning，and usage.However，semantic changes of Chinese unit words happen in a comparatively simple way.The original meaning of these words gets generalized with or without sememes，and the objects they modify get generalized.

Key words: modern Chinese, unit words, original meaning, semantic change patterns, semantic change