Abstract: During the long-term cycling of lithium-ion batteries, potential safety hazards usually arise before severe failure occurs. The conventional external characteristic parameters are difficult to provide timely warning information. The ultrasonic detection technology can determine the changes in the battery structure based on the acoustic response characteristics, thereby providing reliable internal information. This paper introduces the ultrasonic counting to characterize the attenuation of the early cycle life of lithium-ion batteries. Based on the continuous cumulative damage model, the corresponding relationship between ultrasonic counting and battery cycle life is derived, and ultrasonic wave detection experiments are conducted on batteries with different cycle numbers. The experimental results verify the feasibility and effectiveness of characterizing the early cycle life attenuation of lithium-ion batteries based on ultrasonic counting..