In tunnel construction using the drill-and-blast method, particularly in environmentally sensitive areas, blast-induced vibrations are a significant source of potential hazards. As the medium through which stress waves propagate, fractured rock masses play a critical role in the transmission and attenuation of these vibrations. This study aims to investigate the propagation characteristics of blast-induced stress waves through both single joints and jointed fracture zones in rock masses, with particular attention to the effects of joint geometry and material filling. Numerical simulations were conducted using ANSYS/LS-DYNA to analyze stress wave attenuation when a single charge blast impacts an isolated joint, as well as when a delay-blast sequence interacts with a densely jointed fracture zone. The results indicate that: Joints significantly hinder the transmission of stress waves, with unfilled joints exhibiting stronger attenuation effects than filled ones. The inhibitory effect increases with joint aperture. In delay blasting scenarios, wider fracture zones result in stronger impedance, linear reductions in transmission coefficients, and a noticeable decline in energy transfer ratios. Specifically, when the joint width increased from 2 cm to 8 cm, the peak stress attenuation rose from 45.5% to 59.4%. When the fracture zone width expanded from 0.2 m to 1.0 m, the transmission coefficient decreased from 0.95 to 0.76. Moreover, joints effectively reduced the peak particle velocity of blast-induced vibrations and caused a shift from high-frequency to low-frequency components, with the low-frequency effect becoming more pronounced as joint width increased. These findings highlight the significant influence of jointed structures on blast wave propagation in fractured rock masses.