The complexity of torsional vibration testing presents many challenges for analyzing the torsional vibration characteristics. A precise and convenient testing method is very important for establishing the vibration sources, and comparing the experimental results with the numerical predictions. The dynamic testing of vibration can give better pictures of the vibration profile, but it can produce a deformation of the resonance response. The factors causing the deformation were investigated by a numerical calculation method. The result proved that the damping ratio of the system has great influence on the resonance response, and the dynamic testing results of increasing and decreasing frequency are different.A formula for calculating the acceleration time was given especially for the torsional vibration problem of the powertrain. The experimental results give a good agreement with the calculation results.