This paper is aimed to study the influence of aggregate size and inclination angle of joints on the mechanical properties of rock mass. Mortars with two aggregate sizes were used to prepared joint specimens with different inclination angles. Meanwhile

the loading process was monitored by the acoustic emission system. The experimental results showed that the peak shear strength of the specimens increased with the increase of the aggregate size. The peak shear stress of the coarse particle specimen increased firstly and then decreased. However

the peak shear stress of the fine particle specimen exhibited an increasing-decreasing-increasing-decreasing trend. The acoustic emission changed with the loading of the specimen

and reached the maximum value after the peak shear stress.Rock shear fracture criterion was established according to Mohr-Coulomb failure criterion. The stress intensity factor ratio at crack tip（ KⅡc/KⅠc） was found to be only related to the internal friction angle of the rock-like material

and the value of KⅡc/KⅠcincreased with the increase of the internal friction angle.