Values of the Casson Viscosity (CV) and Casson yield stress(CY) in the blood of hamsters and SDrats were obtained by unitary linearly regression. Results : There was not significantly difference inthe CV value between hamsters and rats (p>0.05). Significantly difference was found in the CYvalue (p<0.01). The results suggests that : in the study of the erythrocyte deformabllity propertiesabout diseases and medicines, hamster as well as rats can be act as a good animal model, but in thestudies which have significantly erythrocyte assemble properties, it's better to choose SD rats. Iferythrocyte assemble property is not significant, the hamster may be a better choice. It has animportant significance to popularize and spread the CV and CY in the hemorheology study.