Abstract: Abstract：Eastern Jiaodong, regionally located at the eastern end of the Qinling-Dabie-Sulu orogenic belt, is a Mesozoic strike-slip thrust belt. The study of ultramicroscopic structure is favorable to solving the problem of deformation mechanisms of rocks. Microstructure and ultramicrostructure of the strike-slip thrust belt in eastern Jiaodong have been studied using both microscopy and TEM. Study indicates that the dislocation substructure of quartz in the main strike-slip thrust shear zone is dominated by linear dislocation, and in addition, dislocation loops, bow-out, walls, arrays and net and subgrains are also common. A middle- to low-temperature, plastic deformation environment. can be deduced from the ultramicroscopic dislocation structures of quartz. Furthermore, the average differential paleo-stress values of the Shidao, Rongcheng and Mouping shear zones show a trend of gradual decrease, which seems to be inversely correlated with the trend of temperatures.