There are four kinds of isomorphic "Yiban(一般)" in modern Chinese. From the diachronicity, there is a close connection between them. In Tang Dynasty, the number phrase "Yiban" gradually solidified, and evolved into adjective "Yiban" with the meaning "the same as; general". To Song Dynasty, the adjective "Yiban" gradually become divided into "ordinary or usual". The Five Dynasties period, the adjective "Yiban" further grammaticalized into a partical. In thelexicalization and grammaticalization of "Yiban", statements, metaphorical extension, re-analysis and contextual effect mechanism has played a vital role.