The geometric error of the rotary axis significantly impacts the machining accuracy of the five-axis machine tool. However， its identification is challenging due to the multitude of error terms and high coupling. This paper introduces a novel machining test and on-machine measurement method designed to identify the six position-dependent geometric errors （PDGE） of the rotary axis. Initially， a misaligned tower-shaped artifact， consisting of three layers of misaligned superimposed rectangular blocks， was designed and processed. Subsequently， measurement points were strategically arranged on the bottom and sides of the artifact at different levels， and on-machine measurements were executed. Using the volumetric error model， the identification principle and analytical solution for each error were derived， and uncertainty analysis was conducted through Monte Carlo simulation. Comparing with the ball-bar error identification method， the maximum deviation of the linearity errors E_XC， E_YC and E_ZC are 2.7 μm， -1.7 μm and -1.3 μm， respectively. Meanwhile， the maximum deviation of the angle errorsthe maximum deviation of the angle errors E_AC， E_BC and E_CC are 1.3"， -0.6"， and -2.1"， respectively， with an overall agreement degree of 95.4% for the PDGE. Through the machining test and on-machine measurement， the identification principles and analytical solutions for each error are straightforward， allowing for the identification of the six PDGE of the rotary axis under actual working conditions.