Abstract: Some shortcomings associated with the existing CAD softwares when simulating plain colored fabrics are analyzed,and the mathematics model for yarns is set up.Based on the glisten principle of woven fabric floats,the mathematics model for glisten brightness is given in which the glisten brightness of each point on the float is correlated with yarn bending,twist direction,yarn section shape and so on.The methods of calculating and creating fabric simulation are presented and the simulation picture of plain colored woven fabrics is shown.After optimizing these mathematics models,the vivid reality sense of simulation picture may be resulted.