Polyethylene pipeline is an essential infrastructure of gas distribution network, and there are some problems such as complex damage assessment and tedious assessment process. How to choose an effective damage assessment method for polyethylene pipelines is the focus of the implementation of the gas distribution network at present. In this paper, a nonlinear directional WAVE method is proposed to detect the damage of polyethylene pipeline by an acoustic WAVE, and the damage results of polyethylene pipeline are searched. The rationality of this method is verified by calculating the aerodynamic equation.The results show that the nonlinear fixed WAVE method can accurately determine the damage and crack propagation degree of the pipeline and simplify the damage assessment process, and the results are superior to the linear directional WAVE method. Therefore, the nonlinear directional WAVE can be used to assess the damage to ethylene pipelines in gas distribution networks, which has strong rationality and practicality and provides support for the actual pipeline damage assessment.