The periodic wear on rails with wavelengths between 20 mm and 100 mm is called short pitch corrugation and the state of the wheel/rail rolling contact with short pitch corrugation is highly non-steady. This paper focuses on characteristics of wheel/rail longitudinal creep forces due to sinusoidal short pitch corrugation on the rail based on Kalker's variational method. It is found that longitudinal creep forces from a nonsteady-state model have decreased amplitudes and phase lags compared with the results from the steady state theory. A system identification method is used to analyze the properties of longitudinal creep force. For sinusoidal short-pitch corrugations of a similar depth, the fluctuating component of the longitudinal creep force can be described using a transfer function of a dimensionless frequency defined as the ratio of the semi-axis length of the contact patch to the wavelength of the short-pitch corrugation. Finally transfer functions are used to calculate the non-steady longitudinal creep forces under multi-wavelength short pitch corrugations and results are in good agreement with those obtained from the variational method.