Dislocation microstructures of olivine from metaperidotite of Songshugou ophiolite in eastern Qinling were studied by means of transmission electron microscope (TEM)，and the result shows that there exist several kinds of dislocations，such as free dislocations，dislocation walls，subgrains，dislocation bows and dislocation loops .These dislocation microstructures resulted from complex creep of olivine in the process of high temperature plastic flow in the upper mantle·According to the average free dislocation density of olivine (2.51 ×108cm-2) and the average size of subgrains (1.636um)，their flow stresses (δ1-δ3), flow strain rate (ε) and viscosity (η) should be 151.3 MPa, 1.17 × 10-15/s,4.31× 1023 Pas and 113.0 MPa，1.307 ×10-9/s，2.88 × 1017 Pas，respectively. Based on the average size of recrystallizations (0.89}um)，it is estimated that the flow stress of the upper mantle is about 15. 8 Mpa，the flow strain rate about 9. 89×10-8/s，and the viscosity about 5.3 × 1014 Pas. These different types of dislocations suggest the different phases of plastic deformation that the host mineral experienced.