Radiation degradation of polyvinyl alcohol (PVA) was shown by-reduced viscosity. Samples were irradiated with. ,60,Co ,γ, -rays and their viscosity was measured in distilled water at 30℃ to determine the reduced viscosity. The formula used to express the radiation degradstion was the simple relationship between the intrinsio viscosity and the absorbed dose,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648483&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648486&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648485&type=,The method of determination of D,0, was described. The ,α, value calculated from experimental data is identical to the value of ,α, in Mark-Houwink equation ,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648475&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648493&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648490&type=,. By correlating the two equations, the value of p,0, (fracture density) and G (main chain fracture) were calculated. The initial number average degree of polymerization ,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648495&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648497&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648496&type=, derived from the value of D,0, and p,0, is approaching to the value of ,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648508&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648510&type=,http://html.publish.founderss.cn/rc-pub/api/common/picture?pictureId=42648499&type=, determined by viscometric method.