Precision measurement of vibrations velocity propagation in solid body (components of power constructions) is discussed to control elastic properties of material and reliability forecasting. The ultrasonics velocity measurement method is based on the determination of the full phase shift of ultrasonic vibrations, coherent to base generator electrical oscillations. Ultrasonic vibrations are formed as long radio impulses, the maximal length of which is selected from the condition of reverberation influence exception on the measured phase shift result. The quantity of full phase cycles in phase shift is done by additional phase measurement on other frequencies, which differs little from the first frequency. The complete phase shift expression and time delay of ultrasonic vibrations is given. The US-velocity measurement method was used for longitudinal and transverse waves, propagated on the same trajectory. Using this, real Poisson's ratio construction material was determined. Analyses of reliable accuracy of ultrasonic velocity measurement and the results of experimental research is given.