In this paper, we consider stabilization for a one-dimensional wave equation with van der Pol type boundary that covers the antistable boundary as a special case. Owing to the energy injection and the nonlinear terms, the uncontrolled plant may lead to a variety of dynamical behaviors such as chaotic acoustic vibration, period-doubling bifurcation, and so on. By exploiting a completely new approach, a novel output feedback law is proposed by using boundary displacement observation only. The well-posedness and the exponential stability of resulting closed-loop system are proved. Some numerical simulations validate the theoretical results.