This paper presents the double-flank rack probe (DFRP) method to measure the accuracy relevant to flanks of gear teeth. In DFRP method, both left and right flanks of the gear to be measured are in mesh with a rack probe to measure pitch and profile deviations on the left and right flanks simultaneously. A gear measuring device (GMD) using DFRP method is developed. The evaluation method for pitch and profile deviations, the structure of the measuring system, and the key mechanical parts are introduced. Repeatability experimental results of the device is less than 2 μm, and the results compared to the gear measuring machine (GMM) Klingelnberg P26 shows that this device have consistency with GMM and can be used for the measurement of the accuracy relevant to flanks of gear teeth.