A simple method for estimation of the differential nonlinearity for the velocity driving systems in Mössbauer spectrometers using the reference absorber of the thin α-Fe foil is presented. This method was applied for testing the differential nonlinearity of velocity in Ranger Electronics, Wissel and SM-2201 spectrometers. The results demonstrated a significant differential nonlinearity in the case of out-of-tune velocity driving system while adjusted spectrometers showed comparable differential nonlinearity below 0.4%.