Abstract: It is difficult to use analytic method to solve sound fields scattered by a finite cylinder. The approximate methods of numerical calculation can be used, but the Physical intuition is lacking. In this article an approximate theoritical anlytic model is proposed. It is based on sound excitation and reradiation of the elastic helical surface wave. In certain range of incident angle, the echo's pulse response of finite elastic cylinders is analysed, as well as foundamental representations are derived for calculating the time sequence of echoes and the resonance modes of cylinders. In experimental tank, the time-sequence of pulse echoes for steel and aluminum cylinders are measured, experimental results are basically in agreement with theoretical results.