This publication includes information about problems of pile foundation inspection using non-destructive methods. There is no information on how to measure the length of the pile using seismo-acoustic method in modern Russian standards. This raises the question of the applicability of this method to monitor the piles and the factors that affect the result of measurement. Results contain length measurements, performed on steel pile-shell with an open end in a variety of conditions. The result is the confirmed possibility of seismo-acoustic method for controlling the length of piles of this type. The influence of the surrounding environment on pileaccuracy was found.