This paper studied the nonlinear vibration of an axially moving beam with coupled transverse and longitudinal motions, and the focus was on the internal resonance in the neighborhood of a 1:3 between the first two transverse modes. First, the motion equations of the axially moving beam are derived through the Hamilton’s principle, and were discretized by the Galerkin’s method to obtain the quadratic and cubic nonlinearities. Then, the IHB method was applied to analyze the complicated frequencyamplitude response curves, thus obtaining the nonlinear vibration of the axially moving beam near the first two transverse natural frequencies with coupled transverse and longitudinal motions, which reveals the rich and interesting nonlinear phenomena.