Abstract: FT-IR spectrometry was applied to the testing of paraffin,which is illegally admixed with buffer used in chafing dishes.About 1 g of butter bought from the market was taken as a sample and saponified in 30 mL of 2 mol·L-1 alcoholic solution of potassium hydroxide.The saponified solution was quick-frozen and the floats on the surface were pick up with a self-made bamboo slice and transferred onto the testing plate of the IR-spectrograph.IR-determination was made by scanning in the wave number range of 450 cm-1 to 3 500 cm-1,and qualitative analysis was performed at 721 cm-1.A significant IR spectrum was observed even when as low as 0.05% (mass fraction) of paraffin was added to a blank sample of butter.