We study statistical properties of energy bursts in a polycrystalline metal under uniaxial tension. Using acoustic emission (AE) technique, we measure the amplitude of AE waves and then analyze the statistical properties such as the maximum amplitude distributin, P(A_0), and the amplitude per unit avalanche event,P(A). As a result, we found that power law behaviors of both the maximum amplitude with the exponets have neatly same value with α=β〜3.0±0.1, which is twice of that of single crystalline metal reported in the literature.