A magnetic coupling assembly has a supporting base, a first disk, a second disk and two piezoelectric actuators. The piezoelectric actuators are mounted between the supporting base and the first disk to drive the first disk to move along an axial direction of the supporting base and to adjust the air gap between the first and second disks. Each piezoelectric actuator has a housing, a pushing arm and at least one piezoelectric block. The pushing arm is mounted slidably in and extends out of the housing along a longitudinal direction parallel with the axial direction of the supporting base and has an end securely connected with the first disk. The at least one piezoelectric block is mounted in the housing and is attached to the pushing arm to push the pushing arm to move along the longitudinal direction.