This paper investigates the damping property of a recycled concrete beam with prefabricated cracks through the lens of free vibration attenuation. The experiment is designed to evaluate the effects of various recycled aggregate replacement percentages and fracture depths. The frequency and damping characteristics of recycled concrete and cracking, as well as their evolution through time, were explored, as well as the influence of a variety of factors and their interactions. For various recycled aggregate replacement ratios, the testing results indicate that the frequency of free vibration is between 3000 and 4000 Hz. The damping ratio of unconstrained vibration varies between 0 and 0.04 and is typically about 0.015. The analysis demonstrates that as the replacement ratio of recycled aggregate increases, the average frequency decreases but the damping ratio increases overall; vibration frequency has a parabolic relationship with the replacement ratio of recycled aggregate but a linear relationship with the crack depth; and damping ratio has a parabolic relationship with the replacement ratio of recycled aggregate. The average frequency decreases as the recycled aggregate replacement ratio increases. The average frequency decreases as the recycled aggregate replacement ratio increases. The frequency of vibration is proportional to the recycled aggregate replacement ratio and is linear in relation to the crack depth. The damping ratio and the recycled aggregate replacement ratio are related to the crack depth in a parabolic fashion. In the test, no statistically significant relationship exists between the vibration amplitude and the damping ratio.