In order to study the propagation characteristics of stress wave in rock mass with filling joints, the Three- Dimension Distinct Element Code was used to explore the influence of different occurrence joints on the penetration and reflection rules of P wave. First, a computational model of three-dimensional jointed rock rods was established, and the transmission boundary and Rayleigh damping were reasonably selected. Then, the calculated results were compared with the theoretical solutions of equivalent wave impedance to verify the rationality of the model. Finally, the variation characteristics of P wave transmission and reflection coefficient at different joint angles, thicknesses, spacing, numbers and incident wave frequencies were considered. Results show that when the azimuth angle of joint inclination is 0°~60°, the transmission coefficient decreases with the increase of beta, but increases with the increase of beta when the azimuth angle is 60°~90°. The transmission coefficient decreases with the increase of the incident wave frequency, while the reflection coefficient decreases. If the proportional relation between joint spacing and thickness is defined, the transmission coefficient increases with the increase of joint spacing, while the reflection coefficient decreases. In addition, according to the number of joints under different thicknesses of the joint and transmission (reflection) shot coefficient curve characteristics, its envelope for critical transmission (reflection) curve is defined. Then, when the number of joints is given,
the transmission (reflection) coefficient is larger (smaller) than the corresponding value on the critical transmission (reflection) curve.