Abstract: Arbitrariness refers to the absence of logical and prior relation between sound pattern and concept it stands for. From an integrational point of view, however , arbitrariness manifests itself in the binary opposition of linguistic signs an d their entities, sound and meaning, or syntactic structure and its semantic cont ent. Antithetical to arbitariness is non-arbitrariness, which includes motivati on and iconicity. Motivation is any driving force that promotes a language's bir th, development or death. Iconicity is concerned with the corresponding relation between syntactic form and semantic function and it is an indispensable complem ent to arbitrariness. Complementary to each other at different linguistic levels , arbitrariness and non-arbitrariness are two functional principles of language formation.