This article starts with an outline of Malaysian Chinese. Then, it examines the unique formation and development process of the oral and written language from the diachronic perspective. Combining with its environment of multi-languages contact and competition, this article summarizes three linguistic features of Malaysian Chinese including the following: the phenomenon of code-switching and code-mixing, the intermixture and distinction of oral and written forms, and the remarkable impacts of source dialects (Cantonese, Hokkien, and Hakka). Based on the discussion, we believe that Malaysian Chinese has a practical research value as a extraterritorial variant of the standard language of modern Chinese.