Abstract: The effect of thickness and density of the melamine foam on the sound absorption coefficient was analyzed by impedance experiment.The data show that density has only little effect below frequency 400 Hz,and the thickness has more effect on the acoustic absorption than density.A comparison was done between melamine foam and fiber absorbing materials.The melamine foam has lower absorbing coefficient below frequency 1 kHz and higher than the fiber absorbing materials.Another comparison was done between melamine foam and polyurethane foam.The melamine foam has similar absorbing coefficient at low frequency bands(<1 kHz),at medium frequency and high frequency bands(≥1 kHz) melamine foam had higher absorption coefficient than other foams.