Large-scale crustal extension happened in Northeast Asia continent during the Late Mesozoic, represented by metamorphic core complex and asymmetric granite domes. The extensional shearing mechanism has always been one of the important issues in tectonic research. Three asymmetric extensional granitic domes, including Hanwula, Nalan and Baoder, are spread along the southeast section of the China-Mongolia boundary in the NE direction. The main body of these domes are the Late Mesozoic granitic intrusions. Ductile shear (mylonitic) zones are developed in the northwest margin of these domes, which are confined by the later high-angle normal faults. According to the structural relationships between the strongly deformed medium coarse-grain K-feldspar granite (133±1 Ma) and the weakly deformed fine-grain granite (128±2 Ma) in the ductile shear zone of the Hanwula dome and their zircon U-Pb ages, it is inferred that these granites may be syn-extensional intrusions, and the timing of ductile extension is after 133 Ma and lasts to 128 Ma or later, which is the same as the development time of other domes in the NE Asia. We use R_f/ф method to measure the finite strain axial rates of feldspar in mylonites from the three ductile shears, Hsu diagram shows that the strain type is plane-flattening strain type (average k=0.5). Polar Mohr circle method, the rigid particle network method and the C-axis quartz fabric method are used to estimate the long-term deformation processes of ductile shearing. The methods gave average kinematic vorticity values of 0.68~0.74 of mylonites, which indicated that the ductile shearing of these domes was dominated by general shear with nearly equal pure shear and simple shear components. Kinematic vorticity values of the later stage of ductile deformation obtained by the quartz diagonal strip method are 0.87~0.99 with an average value of 0.93, which indicated that the ductile deformation converted from general-shear-dominated to simple-shear-dominated. However, kinematic vorticity values obtained by the C' (stretch fold cleavage) method are 0.53~0.74 with an average of 0.68, which indicated that the latest incremental strain in progressive deformation process is mainly pure shear. The results show that the ductile shear detachment zones of these domes are mainly formed by general shear. In the early stage, the simple shear component gradually increased. In the later stage,the simple shear component decreased due to the processes of magma upwelling and overall exhumation. The shear deformation is dominated by pure shear. Compared with other extensional domes and metamorphic core complexes in NE Asia at the same period, this kind of shearing pattern may be general significance.