The principle of wave-gate tracking and the demand of adaptive wave-gate were introduced.The adaptive wave-gate tracking algorithm based on the Snake model was proposed according to the GVF Snake model in the active contour models and adaptive centroid tracking algorithm.Then the position and size of the wave-gate were ascertained on the basis of the convergence contour of the Snake model and the updating of the wave-gate was determined by the proportion of the background pixels in it.The experiment and simulation show that the algorithm can change the size of the wave-gate adaptively and track the target well.