This study addresses the challenges of measuring inner hole parameters in workpieces with large depth-to-diameter ratios by proposing a rotating measurement method based on spectral confocal principles. First, a measuring system tailored for inner hole parameters with a large depth-to-diameter ratio is designed and constructed. An optical confocal probe that allows for non-contact measurements is next mounted at the front end of a hollow, long, straight guide rod. This guide rod is driven by an X-R_Xmotion module that facilitates the rotation of the optical confocal probe in the direction of the hole's depth. Then, 10 groups of experiments are conducted at various speeds to collect inner diameter data from the spectral confocal probe, which rotates forward and reversely alternately three times each within an inner hole workpiece characterized by a depth-to-diameter ratio of 12.52 and depth of 222 mm. Finally, algorithms are developed to calculate the diameter, center coordinates, and perpendicularity of the inner hole by fitting the contour of the inner hole workpiece using the inverse least squares method. The analysis also considered the effects of moving speed on the measurement accuracy of the inner hole parameters. It is verified by comparison experiment that the system has high measuring accuracy. The measuring value of hole inner diameter fluctuates within ±2 μm and the perpendicularity within 50 μm under low speed, while those are within ±7 μm and 80 μm under high speed. The results align closely with the calibration values for large deep-diameter workpieces, thus demonstrating the effectiveness of the proposed method and system.