THis paper presents a useful measuring method for rapidly verifying geometric errors using a double-readheads planar encoder system. The system is capable of comparing the displacement measurements between two parallel lines simultaneously when the machine axes are moved. With the calculated model and the various specified test paths, the proposed measuring method provides rapid performance, simplicity of set-up, low cost and pre-process verification of computer numerical control (CNC) machine tools. Complete set-ups and procedures for geometric error verification are clearly presented. Also, the proposed system tested the dynamic performance of the CNC machine tools. It is an integrated system that can complete both dynamic performance and the geometric verification of CNC machine tools.