Geometric errors are important error sources of the computer numerically controlled ( CNC) five-axis machine tool. The conventional measurement methods and instruments are expensive and have a long measurement period. To address these issues, a fast identification method for geometric errors of a five-axis machine tool based on a double ball-bar is proposed. For the errors of linear axes of the machine tool, a spatial error model for linear axes is formulated, which is based on the multi-body system theory and homogeneous coordinate transformation. By measuring two circular trajectories of a double ball-bar (DBB) at different positions on the same plane, 4 key linear errors of the linear axes are identified. For the rotary table and swing axis of the five-axis machine tool, 12 geometric errors of the rotary axes are ascertained using the axial, radial, and conical measurement modes of the DBB, combined with the polynomial model. The experimental results of angle positing error show that the maximum error of the proposed method is 0. 001 8°, compared with that of the laser interferometer method. By using the identification results of the machine tool space error, the error of the test track is reduced from 16 μm to 4 μm, which is 25% before compensation. It evaluates the effectiveness of the method. The proposed method of geometric error identification for five-axis machine tools is convenient, and suitable for the industrial field.