Abstract: The good caustic solubility of both the soybean protein and the cellulose sulfonate makes it is possible to develop a new protein modified cellulose fiber by polyblending.And the polyblend structure and performances of this new fiber are discussed.It shows that the soybean protein /viscose polyblend fiber is a kind of protein modified viscose fiber,which possesses the advantages of both the protein fiber and the cellulose,especially the better wettability and the natural style.