There are several factors affecting the strength of welding seam through hot air for PVC-acrylic coated polyester fabrics. To obtain the most durability of the welding seam for practical use, the experimental design of this study adopts Taguchi method for determining a number of experiments. Each input parameter has five different levels. The result shows that the input parameters providing maximum failing load for welding in warp and weft directions are the following: the distance between a head of blower and workpiece (Dis) of 10 mm, the temperature of hot air (Tem) of 160 o C, the torque (Tq) of 9,000 N.mm, and the speed of hot air (Sha) of 4,000 mm/s. The maximum failing loads are 95.38 kN/m and 86.17 kN/m for warp direction and weft direction, respectively. After filtering the input parameters at the significance level of 0.05, the input parameters which significantly affect the strength of welding seam are the distance between a head of blower and workpiece, and the temperature of hot air. Additionally, the relationship between the input parameters and the failing load seams can be establishad. The comparison between the actual experimental data and the predicted values of the failing load for both welding directions shows that the average percentage error is less than 0.1% so that the forecast equation is appropriate for the explanation of the variables for this study and provide statistical reliability.