To achieve precise measurement of the dynamic radius of a precision centrifuge， an external reference measurement system was established utilizing dual-comb ranging technology. This approach capitalizes on the advantages of high speed， exceptional precision， and absolute distance measurement， and incorporates a spatial optical configuration featuring a cylindrical mirror and focusing path. Initially， the structure and principles underlying the external reference measuring device based on dual-comb ranging are presented. Subsequently， an analysis is conducted regarding the influence of curvature radius and alignment errors of the cylindrical mirror target on the precision of dynamic radius measurements， accompanied by the proposal of a method for mutual compensation error correction. An experimental system has been constructed to assess the dynamic radius of the precision centrifuge across various acceleration levels. Both static and dynamic measurement precisions of the system are evaluated， and sources of measurement errors are identified alongside a proposed system optimization plan. Experimental results demonstrate that the system effectively measures dynamic radius variations under accelerations ranging from 0g to 15g. With 20 sliding averages at a repetition frequency difference of 2 kHz， the dynamic measurement accuracy exceeds 0.56 μm， with a maximum dynamic radius recorded at 204.90 μm. This methodology satisfies the stringent requirements for high-speed and high-precision dynamic radius measurements， thereby enhancing the accuracy of centrifuge acceleration calibration.