Abstract: In order to obtain the sound absorption coefficient of sound absorption material, a simulation method of impedance tube based on Virtual.Lab Acoustics platform is proposed. The acoustic model of impedance tube and specimen is established, and the complex sound pressure at the measured point of microphone is extracted. Then, the transfer function and sound absorption coefficient at the measured point of microphone are obtained based on the distance between microphone and the distance between microphone and specimen. By comparing the calculated results with those in literature, the correctness of the transfer function and the calculation method of sound absorption coefficient in this paper are verified. The influence of impedance tube diameter and microphone location on the calculation of sound absorption coefficient is analyzed by simulation. It is shown that the location of microphone measurement point can affect the calculation of sound absorption coefficient, and the acoustic modes in the impedance tube should be considered for the measurement point arrangement. Quantitative calculations are made for the influences of the specimen tilt angle, specimen thickness and the rear air column of the specimen in the impedance tube on the sound absorption coefficient.