Abstract: The current pattern preparation system of computerized flat knitting machine usually doesn’t have the three-dimensional (3D) knitted fabric simulation function. In this paper, the 3D simulating method of knitted fabric is studied by introducing the virtual reality (VR), and a 3D simulation system of weft knitted fabric is developed. The developing method, characteristics and main functions of the system are presented. The key technologies including 3D loop model and its visualization, 3D parametric simulation of the weft knitted structure and interactive design on network are described in detail. A new method is provided to complete 3D simulation functions of knitted fabric and moving process simulation of the implementation parts in flat knitting machine. The approach, which is proposed to simulate the knitted fabric 3D appearance interactively on network, can be used as a foundation for further study of the virtual design of textile on the web.