This paper presents a method for modelling the seam puckering of multi-layer fabrics by considering the thread shrinkage as well as seam structure and fabric compression properties. A theoretical investigation and numerical calculation of forces acting on the sewing thread were carried out. Based on this, the forces causing the thread tension puckering were analyzed and a seam model to calculate the deformation of a multi-layer seam when threads shrink is presented. Three types of seams were simulated and satisfactory results were obtained