Traction is the key to ensure the smooth out of the product. The traction depends on the shear stress between the fiberglass product and the pultrusion mold. The shear stress decreases with the increase of traction speed, and there are three peaks in the entrance, middle and exit of the mold. The peak of the population is generated by the viscosity of the resin. Its size depends on the nature of the fluid, the entrance temperature and the content of the filler. The viscosity of the resin in the mold decreases with the increase of temperature, and the shear stress decreases. The viscosity and shear stress increase with the curing reaction. The second peak values are corresponding to the detachment point, and the increase of the speed of traction is greatly reduced. The third peak in the exit is the product after curing and the mold wall friction and produce, its value is small. Traction is very important in pultrusion process control. To make the product surface smooth, the shear stress from the point of departure is required (the second peak value) is small, and the mold is as soon as possible. The change of the traction is the reaction of the product in the pultrusion mold condition, and product shape and size, release agent, temperature, traction speed and many factors will affect the traction.