Abstract: The establishment of a planetary atmospheric acoustic platform with an acoustic testing environment is of great significance for deep space exploration. The selection of wind tunnel sound-absorbing materials is crucial for the construction of anechoic capacity in the acoustic testing environment. Sound-absorbing materials are required to have low temperature resistance and the ability to be used in low pressure after experiencing high vacuum. In this paper, for the requirements of sound-absorbing materials for the acoustic wind tunnel of the planetary atmospheric acoustic detection platform, three fiber candidates were selected with the average sound absorption coefficient α greater than 0.5. Their low-temperature resistance, sound-absorbing performance in the frequency range of 200-6300 Hz and outgassing rate under vacuum were compared. The non-adhesive long fiber white glass wool was determined as the sound-absorbing material for acoustic wind tunnel, and its feasibility in the acoustic wind tunnel for planetary atmospheric acoustic detection platform was further verified.