Writing is one of the key words in Derrida’s deconstructive philosophy. In his Of Grammatology, Derrida refers to the claims of writing from Plato to Rousseau and down to Saussure, confuting their idea that writing is the image of speech".However, Derrida, inspired by Saussure’s principle of difference that "in language there are only differences,"and expounds the relationship between writing and differance, by which he transforms Saussure’s static difference into the dynamic differance. Writing plays the game of difference in simulacra, and fills up the simulacrum in the supplemental movement of "image", Writing finally becomes a roaming orphan, which is nothing but the simulacrum.