Abstract: The dissolving of the water-soluble polyvinyl alcohol(PVA) fiber in the ply yarn is the key process of fabric manufacturing with untwisted yarns.Control of dissolving time has been a long-standing problem in the product development associated with PVA blends.To control the optimal time,two methods were designed,i.e.,yarn strength testing method and weight method.The results of the two methods showed coincidently that the PVA of the ply yarn could be dissolved probably in 30 minutes.And this conclusion provides a reliable parameter for industrialized production.