Arbitrariness of linguistic sign has long been controversial in academic circles both at home and abroad. In China, this issue has been under heated debate since Professor Wang Ying published in 1999 his book On Iconicity of Linguistic Sign - A Challenge and a Complement to Saussure's Arbitrariness of Linguistic Sign. In the meantime, Saussure's arbitrariness has been questioned and his whole theory on linguistics and semiology challenged. As is known to all, Saussure's theory is the basis of different schools of modern linguistics and arbitrariness is one of the cornerstones of the theory, this debate, therefore, is of extremely great significance. The author believes that Saussure's linguistics and semiology on the one hand and Peirce's semiotics on the other, are two entirely different systems. Saussure's system in general and his theory of linguistic arbitrariness are not supposed to be judged by Peirce's theory of iconicity. Otherwise the debate will be inconclusive and will surely cause further confusion. Consequently, a thorough and clear comprehension of the essentials of these two systems is the prerequisite for the solution of the issue..