Static shear-rheology for self-made semi-solid AZ91D magnesium alloy slurry was studied by using the tester and a universal electronic machine. Shear-stress along with cylindrical surface in the sample was produced by using the tester and then shear-rheologic deformation happened. It showed that on the condition of the same loading, the longer the loading time and holding time were, the larger the deforming rate was. When the holding time attained a certain value, small grains acquired enough energy to grow up or amalgamate with prolonging the holding time and coarse grains started to melt from intergranular or grain boundaries, but the critical shear-stress kept a constant. The sample didn’t flow but appeared to instantaneous shear-strains with starting to load. When the loading exceeded the critical value, the sample started to flow and had the phenomena of elastic after-working, elastic before-working and remained deformation. The rheologic characteristics of semi-solid AZ91D magnesium alloy were expressed by the five element mechanical model: H1—(N1/H2)—(N2/S).