Modeling fabrics with yarn models makes the fabric structure more realistic in detail. In this paper, a fiber-level rendering method is proposed to simulate different yarns and fabrics. The fibers are divided into three categories: the ply, the loop hairiness and the short hairiness. Geometric tubes are modeled to match these fibers according to the input yarn parameters. Different fibers can be selected depending on the yarn type, which is flexible to reduce the computation amount. Texture mapping is applied to simulate the yarn surface, reducing the memory and time cost of rendering large numbers of fibers. Several single yarns and fabric with different structures are simulated, demonstrating that this is an effective method for fabric modeling and rendering.