【Objective】The present experiment was conducted to investigate the viscosity characteristics of different yam （Dioscorea opposita Thunb.） germplasm resources to provide reference for its application in varietal breeding program. 【Method】The viscosity of different yam germplasm was determined and data were utilized in performing cluster analysis. 【Result】The coefficient of variation in viscosity of 15 yam germplasm （varieties） was 56.18%， which showed rich polymorphism. The highest viscosity was observed in variety GY44 （81.6 dpa.s）， followed by Guihuai 2 （74.3 dpa.s） and GY17 （71.7 dpa.s）. Among different types of yam germplasm （varieties）， the viscosity in its decreasing order was: long-heart leaf type >tetragonous stem type>wild type>three-lobed leaf type. On the basis of cluster analysis， the fifteen yam varieties（germplasm） were classified into 3 types， viz.， high-viscosity type， middle-viscosity type and low viscosity type. 【Conclusion】The yam variety GY44， Guihuai 2 and GY17 can be used as intermediate material in breeding programs. The differences in viscosity parameter could be used as criteria for classifying yam germplasm resources.