Abstract: The computational model for anchorage resistance is the core problem of the theoretical researches anchorage of jointed rock mass, and the anchorage mechanism of filling jointed soft rock is more complex and not yet clear. Based on the theory of structural mechanics, the constraint stress in the extrusion deformation zone of the bolt is regarded as a rectangular distribution mode, and the value of the constraint stress is modified to a formula expressed by the strength ( \sigma _j ) and filling degree ( \varDelta ) of the filling materials. The mechanical model for anchorage resistance of filling jointed soft rock considering large deformation of rotation angle is established. The shear tests on the anchored filling jointed rock mass under the constant normal stiffness (CNS) boundary are further carried out for verification. The research results show that under the influences of the mechanical boundary of deep rock mass, the ratio of the length of the shear deformation section of the anchor rod to its diameter is basically between 0.7 and 1.5. With the increase of \varDelta , the theoretically calculated values of the shear contribution rates of the anchor rod are 9.8 %, 16.5 %, 22.0 % and 34.8 %, respectively. The ratio of the joint surface resistances provided by the shear force and the axial force is reduced from 2.83 to 0.72, indicating that when the anchorage angle \beta = 90^ \circ , the shear force first bears the main resistance behavior. When a large angular displacement occurs, the shear force no longer significantly increases, and the resistance behavior is gradually provided by the axial force until the anchorage system fails. Further, the distribution characteristics of bolt resistance under the condition of \beta = 30^ \circ \sim 90^ \circ are analyzed, and the rationality of the model is verified, which can provide reference for the anchorage design theory of jointed rock mass.