For prefabricated members, the reliable bonding of new-to-old concrete interface is the key to the formation of an integrated load-bearing system. Currently, both domestical and international scholars have conducted a series of studies on the static performance of the interface. However, the structures are often subjected to dynamic impact loads such as vehicle and ship collisions, heavy object impacts, and natural disasters during their service. Therefore, this paper studied the dynamic mechanical performance of the interface between new and old concrete in prefabricated structures. 210 prefabricated concrete components were investigated based on the split Hopkinson pressure bar test method. The research factors of this experiment include key parameters such as the average groove depth, the number of grooves, the interface inclination angle, and the combination of strength grades of new and old concrete, as well as the interface treatment methods (bonded rebar or not). The results indicate that factors such as the impact air pressure and the inclination angle of the specimen interface have a significant influence on the failure modes of the specimens, which can be classified into five categories based on the degree of damage and crack development characteristics. As the impact air pressure increases, the strain rate of specimens with different interface inclination angles gradually increases, with the 20° inclination angle specimens showing the most significant increase, while the 40° and 60° inclination angle specimens exhibit similar increases. With the increase in strain rate, the peak stress of all specimens shows an increasing trend. Under the same impact air pressure, specimens with a 40° interface inclination angle achieve relatively larger peak stress when the groove depth is greater, the number of grooves is higher, and the strength grade of the new concrete is increased. Bonded rebar can improve the peak stress of specimens under certain conditions. As the strain rate increases, the interface shear stress of all specimens also increases accordingly. Under the same concrete strength grade combinations, the shear stress of specimens with C1/C3 and C2/C3 is similar, both being greater than that of C1/C2. In particular, specimens with a 40°interface inclination angle exhibit higher shear stress at the interface. For specimens without bonded rebar, interface bearing capacity formulas were derived for three types: static-loaded without grooves, static-loaded with grooves, and impact-loaded with grooves. These formulas show good agreement with experimental results.