To research the bounded damped oscillatory solutions of nonlinear evolution equation, we choose the Fisher equation as an example. The solutions with negative amplitudes of Fisher equation may become meaningful in the context of nonscalar models describing excitable media (e.g. the Belousov-Zhabotinsky (BZ) reaction). The theory of planar dynamical systems is used to study the existence conditions of bounded traveling wave solutions of Fisher equation. The bounded approximate damped oscillatory analytic solution is given by using LS method and linearization method. And its error is also estimated.