Abstract: The joint distribution position has an effect on the comprehensive shear strength of rock mass and controls the initiation and fracture evolution of the locked segment type of a rock slope. The influence degree of the joint distribution on the comprehensive shear strength and fracture characteristics of rock mass is analyzed through model specimen making and shear tests. In the tests the cement mortar is taken as the model material, and the closed joint is prefabricated at different positions of the shear plane, making it a model with the sealing around and the internal joint through. The shear tests are carried out under different normal stresses to determine the variation law of shear strength and shear rupture characteristics. The test results show that the fracture surface of the sample can be divided into three parts: wing-tensile failure zone, wing compression-shear failure zone and end-tensile failure zone. The shear strength parameters also fluctuate regularly with the change in joint positions, and the greater the normal stress, the greater the variation range.