This paper describes the calibration of commercial accelerometers with mass load by laser interferometry at frequencies ranging from 2 kHz to 10 kHz. It is shown by experiment that the effect of mass load on the frequency response of commercial accelerometers with inverted centre mounted compression design is negligible. The comparison method adopted by some foreign companies has been analysed and the relative motion between the top of the mass load and the upper surface of a commercial accelerometer has been measured, thus explaining the obvious errors in frequency response curves obtained by using the comparison method.