Objective To explore the optimal falling height parameters for single-leg drop jump,so as toaddress the bilateral imbalance in the lower limbs of athletes and provide a reference for coaches to design training plans accurately and effectively.Methods Twelve first-grade male athletes were re-cruited for the study,including five track and field sprinters and seven basketball players(age:20.41±1.11 years,height:189.19±9.15 cm,weight:83.50±12.08 kg).The vertical jump platform was used to test the optimal counter-movement jump(CMJ)height for the dominant and non-dominant sides of the subject's lower extremities,and to determine the three falling heights of the low height(medium height minus 5 cm),medium height(50%of the optimal unilateral lower-limb CMJ height)and high height(medium height plus 5 cm).Six parameters of the drop jump performance,including buffer time,leg stiffness,peak vertical ground reaction force(vGRFpeak),the rate of force development(RFD),power,root mean square(RMS)of surface electromyogram signals were collected synchronous-ly using the Vicon Motion Capture System(200 Hz),Delsys portable wireless telemetry EMG test sys-tem and Kistler three-dimensional force platform(1000 Hz).Results(1)At the medium height,the av-erage buffer time,leg stiffness,vGRFpeak,RFD,RMS and power of either leg were significantly bet-ter than at the other two heights(P<0.05),and the leg stiffness of the non-dominant leg was signifi-cantly inferior to the dominant leg(P<0.05).(2)At the high height,the average buffer time,vGRFpeak and RMS of the dominant leg were significantly better than at low height(P<0.05),while the average buffer time,leg stiffness,vGRFpeak,RFD,power and RMS of the non-dominant legs were significant-ly worse than the dominant legs(P<0.05).Conclusion Coaches or athletes can choose the medium height(50%optimal unilateral lower-limb CMJ height)designed in this study and schedule unilateral lower limb drop jump training to optimize the athletic performance of the dominant or non-dominant legs to the greatest extent.However,as the falling height increases,the gap in athletic performance between the bilateral lower limbs tends to become more pronounced(especially at high height),thus the training should focus on strengthening the eccentric contraction ability and stability of the non-dom-inant side to avoid bilateral imbalance.