The attenuation of ultrasonic pulse velocity in various sized concrete specimens under uniaxial compression loading is tested. Tests were conducted on prisms of 25×25×50 cm fabricated with dam concrete(maximum aggregate of 80mm),and standard 15×15×30 cm prisms,10×10×20 cm prisms which were made with the wet-screened components of dam concrete. Ultrasonic attenuation has been shown to increase significantly as distributed damage in concrete increases. Large changes in attenuation with increasing damage levels were found for all specimens at all power levels. Results also show that the rule of ultrasonic propagation in concrete is apparently affected by the scale effect and the effect of wet screen sieve of aggregate. These conclusions proposed can be applied to determining the extent of damage of mass concrete due to the complex load and other environmental effects.