As a high-performance polymer material, polyimide (PI) aerogel holds great promise for applications in acoustic and thermal protection. However, PI suffers from a monotonous pore structure and poor acoustic and mechanical properties, which limit its use in noise reduction. To enhance the overall performance of PI aerogels and expand their scope of application, a polyimide-aramid fiber aerogel (PI-ANF) with low shrinkage, high strength, and excellent sound-absorbing properties was prepared by mixing an aramid fiber (ANF) dispersion with polyimide acid (PAA) and subjecting the mixture to freeze-drying and thermal imidization. Following the incorporation of ANF, the shrinkage rate of the aerogel samples gradually decreases from 37.4% in the pure PI sample to 30.0% in the PI-ANF-8 sample, while the maximum compressive strength increases from 20.3 kPa in PI to 104 kPa in PI-ANF-8. The minimum decomposition temperature of PI-ANF is 430 °C, which still allows the aerogel to be used at relatively high temperatures below 400 °C. When the ANF mass fraction is 3%, ANF incorporated into the PI matrix forms a large number of mesopores capable of effectively absorbing sound waves, optimizing the acoustic performance of the composite aerogel and achieving an average sound absorption coefficient of 0.78. The results indicate that the introduction of ANF effectively enhances both the sound absorption and mechanical properties of PI aerogels, demonstrating significant application potential in the fields of new energy and building materials.