Abstract: Sand velocity in aeolian sand transport is measured using the PIV system (Particle Imaging Velocimetry) in a wind tunnel. The velocity probability distribution of ascending and descending particles, as well the influences of sand ripple on the sand particle motion are analyzed. The results show that velocity distributions of take-off particles and particles during sand movement accord with logarithm normal distribution. The mean incident velocity of sand particles is 1.005-1.4 times higher than take-off ones with different wind speed. It is found that sand ripples play an important role on the sand particles motion, which is a key factor that can not be neglected.