In this study, an accelerometer-based measurement method is proposed to investigate the dynamic behavior of a spur gear pair. Using this method, dynamic transmission errors of a spur gear pair were measured under realistic speeds and torque ranges to capture its distinct nonlinear phenomenon. This measurement employed a set of uniaxial accelerometers tangentially mounted on the flanges of each shaft next to the gears at a certain radius. The tangential acceleration signals obtained from the uniaxial accelerometers were further processed to calculate the dynamic transmission error by using the proposed formulation. This accelerometer-based meas-urement system was implemented with an example of a spur gear pair with perfect involute profiles. As a result, the measured data show that dynamic transmission errors can be measured quite effectively by using the accelerometer-based measurement method pro-posed in this study. The measured data show that significant vibratory magnitudes were observed for spur gear pairs in the torsional direction. Also, strong nonlinear behaviors in their motions were captured in the form of the discontinuity phenomenon of the forced responses of the dynamic transmission error in the vicinity of the resonances. Based on this research, the proposed accelerometer-based measurement system is suitable for measuring the torsional vibrations of the gear pair in terms of the dynamic transmission error. More importantly, a spur gear pair exhibits significant vibration magnitudes with strong nonlinear behaviors under dynamic conditions.