The fluctuation patterns observed in the Cu-Zn-Al alloy are reported and calculated by using a nonlinear approach in this paper.The results show that the fluid-like oscillations of the atom-cells of μm order have exhibited the feature of solitary waves. The oscillation can be maintained by the external driving,and as the internal friction becomes strong,the decay of the amplitude of solitary wave with respect to the time obeys the exponential rule exp (-kt).The calculation is in good agreement with the experimental observations.