Based on the Large eddy simulation(LES) combined with the immersed boundary method(IBM), the centerline of wind turbine wake is investigated in hilly terrain. Through the systematic analysis of the flow line pattern and the distribution law of the turbine wake centerline under different terrain characteristics, it is found that the evolution of the wake centerline is not solely dominated by terrain undulation, but rather there is a strong coupling relationship with the flow line structure induced by the terrain. In order to deeply reveal the intrinsic connection between terrain-flowline-tailgate centerline, this study innovatively constructs a tailgate centerline model applicable to complex hill terrain. The model is verified to be able to accurately portray the changing characteristics of the wake centerline in a continuously undulating two-dimensional hill wind farm scenario.