In order to investigate the influence of fracture parameters (length, angle) on rock wave velocity and dynamic mechanical properties, wave velocity test and impact test were carried out on the RSM-SY5 intelligent acoustic wave detector and a split Hopkinson pressure bar (SHPB) device. The sandstone samples with different prefabricated fracture angles and lengths, and the deformation process of the specimen under impact load were analyzed by utilizing digital image correlation technology (DIC). This approach reveals the variations in wave velocity, dynamic mechanical properties, and energy dissipation characteristics of different angle and length fracture specimens. The results show that there is an exponential relationship between fracture angle, initial damage, and the longitudinal wave velocity of the sample; a linear relationship between fracture length, initial damage, and the longitudinal wave velocity;and a positive correlation between the longitudinal wave velocity, dynamic compressive strength and dynamic modulus of elasticity for different fracture parameters. Differing fracture angles and lengths significantly influence the dynamic mechanical characteristics of sandstone. With increasing fracture angle and length, the dynamic compressive strength and dynamic elastic modulus decrease, while peak strain increases. Notably, when when α from 20° to 40°, the dynamic compressive strength of the sample decreases significantly. Upon exposure to dynamic loads, shear cracks first emerge near the prefabricated fractures, followed by tensile fractures, eventually leading to tensile-shear damage. High strain concentration areas are observed on the specimen surface, forming strain localization zones near the peak stress, primarily seen on the fracture face. The proportions of reflected and absorbed energy in sandstone increase as the fracture angle and length increase, whereas the transmitted energy proportion decreases.