In the discrete element method, the damping coefficient, which is a key parameter for rational simulation, is uncertain and often chosen based on researchers experience. To make the physical model reflect the reality better, in this paper acoustic technology is used to calibrate the damping coefficient. Oscillogram of the acoustic wave generated by the collisions is analyzed and the calibrated damping coefficient is obtained to be 0.5. The calibrated parameters are used to simulate the random packing process of 2000 monosize spherical particles. The final packing density is 0.625, which is in accordance with the classic measurements quite well. Besides the obtained correct damping coefficient, in this paper both the usefulness of the physical model and the practicability of acoustic technology for detecting the collision time are also demonstrated precisely.