Abstract: In this paper,the damage effect was considered into the impact process of lead-free solder specimens.Based on the experimental data,the modified rate-dependent Johnson-Cook model for the Sn3.0Ag0.5Cu and Sn3.5Ag lead-free solders were derived.The stress-strain curves obtained from the modified Johnson-Cook material models and the experiments agreed quite well with each other.It indicates that presented modified Johnson-Cook models are suitable to describe the dynamic behavior of the two lead-free solder materials.