Abstract: This paper is to establish a relationship between wave velocities of concrete pile shaft measured with the ultrasonic wave method and the low-strain reflected wave method.It proposes a simplified formula for the ratio of wave velocity in infinite medium to that in one dimensional bar The viscoelastic theory based on standard linear solid model is adopted in the formulation of the formula.Experimental results show that the ratio of the ultrasonic wave velocity to the 1.054 timed low-strain reflected wave velocity ranges from 1.03 to 1.12.The ratio decreases with increasing in the age,the Youngs modulus and the strength of concrete.