This paper focuses on the dynamic contour errors due to the coordinated five-axis motion. The dynamic contour error for tracking a contour is defined as the difference between the desired contour and the actual responded tool trajectory to the contouring motion command. We present a methodology on modeling the contour error under a 5-axis machining motion that requires moving the rotation axes and translation axes simultaneously. The derivation includes the forward kinematics and inverse kinematics in terms of homogeneous transformation matrices of a horizontal live-axis machine tool. The input to the contour error model is the measured axial error on each axis. Tire output is the contour error caused by the coordinated five-axis motion. The axial error considered in this model is assumed due to the drive dynamics and the friction force. Computer programs are developed for simulation of the contour error caused by the five-axis motion. The simulation results and analyses are also provided in this paper.