According to the color yarns in the fabric, the yarn-dyed fabrics are divided into two categories: single-system-m$acute{e}$lange color fabrics and double-system-m$acute{e}$lange color fabrics. The method for inspecting the density of double-system-m$acute{e}$lange color fabrics is discussed in this study. By analyzing the pattern and color characters of double-system-m$acute{e}$lange color fabrics, color-gradient image is proposed to detect the density. The gray-projection method and correlation coefficient method are selected to locate the wefts and warps. With the help of Fourier low-pass filter, the positions of yarns in double-system-m$acute{e}$lange color fabric are found, and then the density can be obtained by counting the yarns in a unit length automatically. The experiment proved that the method proposed can detect double-system-m$acute{e}$lange color fabric density successfully.